Nudibranch (sea slug) case method: 50 questions

9 p.m. in May. It is day 10 of keeping one Hypselodoris festiva collected from a rocky shore in a 20 L tank. It was about 4 cm when collected; now it has shrunk to under 3 cm and the color seems paler. It crawls over the live rock but has not touched the frozen brine shrimp or seaweed you put in. You test the water daily: ammonia zero, specific gravity 1.024, temperature a stable 19°C.

Which is the most appropriate decision for the owner in this situation?

1. Water quality is normal, so switch to a prepared food and keep watching
2. If you cannot identify and obtain its sponge food, return it promptly to the same shore where it was collected
3. Shrinking is a natural process like molting, so leave it alone and wait a few weeks
4. Add a fish vitamin supplement to the water to restore its strength

AnswerB. If you cannot identify and obtain its sponge food, return it promptly to the same shore where it was collected

ExplanationHypselodoris festiva is an extremely specialized feeder that eats only particular sponges; it will not eat prepared foods, frozen foods or seaweed. A shrinking, fading body is the typical course toward starvation, and it progresses even when water quality is normal. Unless you can identify the sponge and collect it along with the animal, the only life-saving option is to return it to the exact collection spot while it still has strength. Switching to prepared food provides no nutrition; nudibranchs do not molt, and waiting only guarantees starvation. Vitamin supplements have no proven effect on invertebrates and risk fouling the water. Make the decision to return it the same day.

IssuesThe root problem was collecting without confirming what it eats, assuming that a sea creature would eat something. The owner lacked the knowledge that each nudibranch species has a fixed food organism and that keeping one is impossible without securing that food.

ImprovementBefore collecting, check a field guide for the species and its food, and consider keeping it only if you can bring home the animal together with the food it is sitting on. For species whose food is unknown, limit yourself to observing and photographing. If you do start keeping one, set a deadline in advance: return it if the food has not been eaten within a week.

6 a.m. in July. You have kept three Hypselodoris festiva, collected along with a sponge-covered stone, in a 15 L tank for two weeks. Until yesterday they were crawling over the stone, but this morning all three have fallen off the glass and are drifting near the bottom or surface with rhinophores and gills retracted. Last night you forgot to remove food debris, and the water is slightly cloudy and smells fishy. Specific gravity 1.024, temperature 22°C.

Which is the most appropriate first action?

1. Scoop out the weakened animals and move them all to a separate container of freshly mixed artificial seawater
2. They have most likely died, so discard them if they do not move
3. Assume oxygen shortage and turn aeration up to maximum with strong flow
4. Test ammonia and nitrite, change 1/3 of the water with seawater at the same temperature and specific gravity, and remove the decaying matter

AnswerD. Test ammonia and nitrite, change 1/3 of the water with seawater at the same temperature and specific gravity, and remove the decaying matter

ExplanationCloudy, smelly water and every animal falling off the glass at once indicate poisoning from a sudden spike in ammonia and nitrite. The correct response is to measure with test kits first, remove the decayed sponge debris, then change about 1/3 of the water with seawater at the same temperature and specific gravity to lower the concentration. Suddenly moving everything into freshly mixed artificial seawater is dangerous because even slight differences in gravity or temperature add osmotic shock on top. Aeration helps, but strong flow slams weakened animals against the walls and tears them. As long as rhinophores and gills contract when stimulated they are alive, so discarding is premature. After the water change, dim the lights and watch until morning; isolate any that start to melt.

IssuesFood debris was left in a small tank, letting an ammonia source build up overnight. The owner lacked the awareness that a volume as small as 15 L deteriorates very quickly, and had no habit of daily debris removal and water testing.

ImprovementRemove food debris, feces and mucus daily with a pipette, and test and log ammonia and nitrite every day. Always keep water-change seawater ready at the same temperature and specific gravity. Use as much water volume as possible and keep a spare air pump.

Midday in August. Returning from a three-day trip, you find the cooling fan has evaporated the water and the level in the 10 L tank has dropped 3 cm. Specific gravity measures 1.031. The two aeolid nudibranchs are sluggish in the shade of the rock and the cerata on their backs look deflated. You have fresh water and a batch of artificial seawater at 1.024 on hand.

Which is the most appropriate way to bring the specific gravity back?

1. Add 3 cm worth of fresh water all at once to restore the original level and gravity immediately
2. Replace all the water at once with the 1.024 seawater to return to normal
3. Add fresh water a little at a time over several days, lowering it by about 0.001 per day
4. Higher gravity is closer to seawater and safer, so leave it as is

AnswerC. Add fresh water a little at a time over several days, lowering it by about 0.001 per day

ExplanationNudibranchs have no shell, and the concentration of their body fluids is in direct balance with the surrounding seawater. Lowering an evaporation-raised gravity all at once drives water into the cells, swelling and dissolving the body in osmotic shock. The correct method is to add fresh water in small amounts, returning to 1.023–1.025 at a slow pace of about 0.001 per day. Dumping in fresh water and a full water change are both equally fatal sudden changes. 1.031 is far above open-ocean values, so leaving it will also worsen their condition. Afterward, watch daily how open the rhinophores and cerata are; if still shrunken the next day, recheck temperature and ammonia as well.

IssuesThe owner did not anticipate that a fan on a small tank evaporates water quickly and that gravity would spike during a few days away. There was no auto top-off or water-level mark, and no management plan for the absence.

ImprovementMark a water line on the tank and top up evaporation with small amounts of fresh water daily. When away, use an auto top-off or give a trusted person specific instructions for adding fresh water. Log specific gravity daily and look for the cause of any change of 0.002 or more.

3 p.m. in August. You keep two Hypselodoris festiva in a 20 L tank in a room without air conditioning. Coming home, the room is 33°C and the thermometer reads 29°C. Both have deflated gills, cling motionless to the glass, and one has a whitish patch on its body. They were collected from a shore where the water was about 20°C.

Which is the most appropriate first response?

1. Put ice directly in the tank and bring it down to 20°C at once
2. Higher temperature raises metabolism, so give more food to build strength
3. Float ice packs in bags, turn on the air conditioner, and lower the temperature 1–2°C per hour
4. The whitened one is dead, so remove it and watch the rest

AnswerC. Float ice packs in bags, turn on the air conditioner, and lower the temperature 1–2°C per hour

ExplanationSpecies from temperate shores do best around 20°C; 29°C is close to lethal. Shrunken gills and whitening of the body surface are classic heat stress. The response is to float ice packs in bags and lower the room temperature with the air conditioner, bringing the water down at a pace of 1–2°C per hour. Putting ice directly in the water throws off the gravity and stacks osmotic and temperature shock from the sudden difference. This is not a feeding problem; higher metabolism only worsens oxygen shortage and weakening. The whitened animal is alive if it contracts when stimulated; cool it in an isolation container and watch. If melting progresses, isolate it to protect the main tank. The owner lacked the basic premise that cooling equipment is essential for temperate species in summer.

IssuesThe owner did not check the water temperature at the collection site and started keeping a temperate species in summer in a room without cooling. No upper temperature limit was set, and the temperature rise while away was not anticipated.

ImprovementCheck the collection-site water temperature and do not collect unless you have equipment (cooling fan, aquarium chiller) to maintain it. Use a max-min thermometer and set a procedure to act immediately when the limit is exceeded. Leave the air conditioner on when away in summer.

10 p.m. in June. You keep four Hypselodoris festiva in a 30 L tank. The edge of one animal's back has turned cloudy white and is dissolving as if waterlogged, with strands of mucus drifting in the water. A nearby animal is touching that mucus. The water is clear, but you skipped yesterday's water change. Specific gravity 1.024, temperature 20°C, trace ammonia detected.

Which is the most appropriate first action?

1. Gently remove the dissolved part with tweezers to clean the wound
2. Isolate the melting animal in a separate container of seawater from the collection site and change water in the main tank
3. Treat the whole main tank with a fish antibacterial at the standard dose
4. It may heal on its own, so leave it untouched in the main tank and observe

AnswerB. Isolate the melting animal in a separate container of seawater from the collection site and change water in the main tank

ExplanationBody-surface breakdown (melting) is triggered by injury or poor water quality, and recovery is extremely difficult. The top priority here is protecting the other three: move the melting animal, container and all, underwater into a separate container of seawater from the collection site, then remove the source of decay from the main tank and change the water. Touching the dissolved part with tweezers tears the body further and worsens it. Most fish medications are harmful to invertebrates, and copper-based ones are lethal. Left in the main tank, the mucus and broken-down tissue further degrade the water and spread to the others. After isolating, do not touch it; if it has not rallied by the next day, accept that it has reached the end of its life.

IssuesSkipping one day's water change led to detectable ammonia, which very likely triggered the body-surface breakdown. No isolation container or spare seawater had been prepared, so the initial response was slow.

ImprovementAlways keep a small isolation container and either collection-site seawater or artificial seawater at the same temperature and specific gravity in stock. Schedule water changes on fixed days and log them; change water immediately on any day even trace ammonia is detected. Decide in advance that any melting animal is isolated without hesitation.

Evening in April. Looking through a loupe at a nudibranch collected three days ago, you see two white thread-like sacs attached to the edge of its back, moving independently of the body. The animal looks a little thin but has its rhinophores out and is crawling over the sponge. The owner thinks parasites should be removed quickly and picks up fine-tipped tweezers.

Which is the most appropriate assessment of this decision?

1. These are likely egg sacs of a parasitic copepod; forcing them off tears the body, so do not remove them and observe
2. Parasites left alone will kill everything, so pull them out from the base with tweezers
3. Dip it in fresh water for 30 seconds to shed the parasites
4. Add a fish dewormer to the tank to eliminate them

AnswerA. These are likely egg sacs of a parasitic copepod; forcing them off tears the body, so do not remove them and observe

ExplanationWhite thread- or sac-like objects on a nudibranch's back are usually the egg sacs of copepods parasitizing it internally. The parasite itself is embedded in the body, and pulling out the egg sacs tears the host fatally. The correct answer is not to remove them by hand but to observe the animal's condition. A freshwater dip gives a shell-less nudibranch osmotic shock that is lethal within seconds. Fish dewormers kill the nudibranch itself. Parasitized individuals are not rare in the wild; the real countermeasure is to inspect at collection and avoid them. If it keeps losing weight, decide early to return it to the collection site, and do not keep it in the same container as others.

IssuesThe body surface was not inspected at collection, and a parasitized individual was brought home. The fish-keeping rule that parasites should be removed was applied to a nudibranch with a completely different body structure, nearly injuring it with tweezers.

ImprovementInspect the body surface with a loupe at collection and do not take individuals with white attachments or thinness. Decide in advance never to use freshwater dips, medicated baths or tools on nudibranchs. Keep parasitized individuals in a separate container and return them early if they weaken.

Midnight in May. An aeolid nudibranch has been sucked onto the intake of the powerhead used for flow; the rear half of its body is wedged in the gap and it cannot move. There is no sponge on the intake, and the animal is contracting in light spasms. The owner panics, reaches in and tries to pinch the body and pull it out.

Which is the most appropriate first action?

1. Put on gloves, pinch the body and pull it out quickly to minimize damage
2. The sucked-in part will never recover, so cut it off with scissors
3. Reverse the pump direction and wait for it to be pushed out
4. Turn off the power, take the pump apart underwater and free it without pulling on the body

AnswerD. Turn off the power, take the pump apart underwater and free it without pulling on the body

ExplanationPulling a sucked-in body tears the soft tissue between the suction and your hand. The correct answer is to cut the power first to stop the suction, then disassemble the pump underwater and wait for the animal to come free on its own. Working underwater rather than in air is also essential. Pinching with the hand is itself a major cause of tears in nudibranchs, and aeolids can sting your hand with stored stinging cells. Flow cannot be reversed, and cutting with scissors is fatal. Once freed, leave it to rest in a separate container of clean seawater with no flow and watch until the next day. If melting begins, keep it isolated to protect the main tank.

IssuesA flow pump was used without a sponge on the intake. The owner did not understand that nudibranchs cannot swim and cannot resist suction, and had a pattern of reaching in before turning off the power in an emergency.

ImprovementCover every intake and inlet with sponge and run a weak current along the walls. Write the emergency steps—cut power, disassemble underwater, do not touch—on paper and post it beside the tank. Make a habit of checking every animal's position each morning.

Midday in June. To move a Hypselodoris festiva to another tank, you tried to pry it off the rock with a fish net. It was clinging tightly, and when the net pushed it, the edge of its body tore and a piece stayed on the rock. Mucus is oozing from the tear, but the rhinophores are going in and out.

Which is the most appropriate follow-up?

1. Press the torn piece back into place and hold it with your hand until it sticks
2. Take it out of the water and dry the wound to stop the bleeding
3. Do not touch it further; leave it, rock and all, to rest in a separate container of clean seawater with no flow
4. Dab a fish disinfectant on the wound with a cotton swab before returning it

AnswerC. Do not touch it further; leave it, rock and all, to rest in a separate container of clean seawater with no flow

ExplanationNudibranchs have neither blood nor a clotting mechanism in the human sense, so pressing, drying or disinfecting a wound all cause harm. The correct response is to stop touching it, move it together with the rock to a separate container of clean seawater, remove the flow and let it rest. Small tears are sometimes covered by mucus and recover. Exposure to air makes its condition deteriorate rapidly from drying, and disinfectants are toxic to invertebrates. Moving should be done not with a net but by sinking a container of seawater nearby and placing a card in its path so it climbs on by itself. If melting starts the next day, keep it isolated and understand that recovery depends on the individual.

IssuesFish-handling methods were applied directly to a nudibranch, choosing the net—the method most likely to tear the body. The owner did not know the basics: never peel off an animal clinging to rock, and move it by letting it climb on by itself.

ImprovementMove animals by carrying the rock in a container, or by placing a thin plastic sheet in their path so they climb on, then lifting the container out underwater. Decide that nets and tweezers are never used in the nudibranch tank. For non-urgent moves, wait until the animal climbs onto the glass or a card.

Morning in May. You have been keeping a small shore crab and a Hypselodoris festiva, collected together from the shore, in the same 10 L container. This morning, half of the nudibranch's gill plume is gone and the crab is eating something nearby. The nudibranch has retracted its rhinophores and is curled up in the shade of the rock.

Which is the most appropriate first action?

1. The crab has learned its lesson after one bite, so add a divider and keep them together
2. Pinch the nudibranch with your fingers, move it to another container and apply fish medication to the wound
3. Move the crab to another container immediately, and leave the nudibranch untouched to rest and observe
4. Without gills it cannot breathe, so put it in the freezer to euthanize it

AnswerC. Move the crab to another container immediately, and leave the nudibranch untouched to rest and observe

ExplanationCrabs, hermit crabs and wrasses are predators that eat nudibranchs; housing them together leads to predation. The correct answer is to move the attacker, the crab, to another container first and leave the injured nudibranch untouched to rest. Pinching it with fingers adds tears, and medications are harmful to invertebrates. Dividers are often climbed over at night, leaving a risk of repeat attacks. Losing part of the gill plume does not prevent survival, since it also breathes through its skin and can recover, so this is no basis for declaring it dead. Euthanasia should be decided only after consulting a professional, and freezing should never be done on your own judgment. Keep it dark and quiet until the next day; isolate if melting begins.

IssuesPredator and prey were housed together under the misconception that animals collected from the same shore would get along. The root problem was not researching the diet of each collected animal and cramming them into a small container.

ImprovementKeep nudibranchs alone or with the same species only, and never with crabs, hermit crabs or fish. Collect the minimum number of animals and separate each into its own container. Understand that an animal that has been preyed upon has a poor chance of recovery, and consider returning it early.

7 a.m. in April. A Hypselodoris festiva was lying on the floor beneath the tank. It apparently crawled out through a gap between the lid and the glass and fell. Its body has shrunk to about half, is covered in mucus, and the surface is somewhat dry. When you poke it, the rhinophores move slightly. The floor is dry hardwood.

Which is the most appropriate first action?

1. Pinch it with your fingers, toss it into the tank and let the current wash off the mucus
2. Lift it onto a card wetted with seawater, return it to a separate container of seawater, and wait for it to recover without touching it
3. Rinse it with tap water to remove dirt and dust before returning it to the tank
4. A dried body will never recover, so discard it

AnswerB. Lift it onto a card wetted with seawater, return it to a separate container of seawater, and wait for it to recover without touching it

ExplanationA nudibranch that climbs over the waterline and falls wraps itself in mucus and can briefly withstand drying. If the rhinophores move it is alive, so gently lift it onto a card or thin plastic sheet wetted with seawater, return it to a separate container of seawater, and wait for recovery without touching it. Pinching tears the mucus-protected body, and strong flow also causes tears and weakening. Tap water does almost instantly fatal harm through chlorine and the osmotic effect of fresh water. After it recovers, watch for half a day for melting before returning it to the main tank. To prevent recurrence, keep the water level 5 cm or more below the rim and secure the lid with no gaps.

IssuesThe owner did not know that nudibranchs climb the glass and crawl out over the waterline, and left a gap in the lid. The water level was high, and the fall went unnoticed until morning. There was also a knowledge gap in nearly using tap water for recovery.

ImprovementKeep the water level 5 cm or more below the rim, secure the lid with no gaps, and block the filter cable openings. Count the animals every morning and before bed. Keep seawater and a card beside the tank for recovery, and share the recovery procedure with the family.

Night in November. In a 20 L tank housing a tropical aeolid nudibranch, the animal is wedged between the heater and the glass, with part of its body touching the heater. The heater's indicator light is on. The pinched part has turned white. The owner is about to reach into the water bare-handed.

Which is the most appropriate first action?

1. Pull the wedged body out bare-handed and immerse it in cold water right away
2. Lower the heater's thermostat and wait for the nudibranch to leave on its own
3. Switch off the heater, put on gloves, move the heater and wait for the animal to come free
4. Apply a fish burn ointment to heal the burned area

AnswerC. Switch off the heater, put on gloves, move the heater and wait for the animal to come free

ExplanationThe surface of a powered heater is hot, and the contact area suffers a burn. First cut the power to remove the heat source, put on gloves, move the heater itself, and wait for the animal to come free without pulling on its body. Pulling bare-handed causes both tears and stings from the stinging cells aeolids store. Immersing it in cold water causes osmotic shock from the sudden change in temperature and gravity. Lowering the thermostat does not cool the surface right away, and damage spreads while it stays wedged. Fish medications such as burn ointments are harmful to invertebrates. Once free, let it rest in a separate container of clean seawater; keep it isolated if the whitened area starts to melt. Always fit a heater guard and leave no gaps against rocks or glass.

IssuesThe heater had no guard and was positioned so the body fit exactly into the gap against the glass. The safety step of cutting power first was not ingrained, as shown by nearly reaching bare-handed toward a powered device.

ImprovementUse a guarded heater, position it with no gaps against glass or rock, or install it in the sump. Set the tank-work procedure as: cut power, gloves on, move the equipment. Recognize that for tropical species winter temperature control is the challenge, and log the water temperature daily.

Evening in September. After a two-hour outage, power is back and the stopped hang-on filter and air pump have all started at once. During the outage, the two nudibranchs moved right next to the intake near the surface. Relieved by the restoration, the owner is about to head to the kitchen. Nothing is fitted on the intake.

Which is the most appropriate action here?

1. Power is back, so relax, leave it and check where the animals are in the morning
2. Stop the filter, move the animals away from the intake, then restart it
3. Pull the nudibranchs away from the intake by hand and restart immediately
4. The water went bad during the outage, so replace all of it with new seawater

AnswerB. Stop the filter, move the animals away from the intake, then restart it

ExplanationWhen the pump stops in an outage, nudibranchs tend to gather near the still intake. If suction starts the moment power returns, they are drawn in and torn. The correct response is to stop the filter, then either wait for the animals to move away from the intake or guide them onto a card and over to the rock before restarting. Leaving it until morning is too late, and pulling them away bare-handed causes tears. Ammonia rarely spikes during an outage of about two hours, so a full water change is unnecessary and would cause osmotic and temperature shock. After restoring, fit a sponge on the intake and measure and log ammonia and temperature.

IssuesNo sponge was fitted on the intake, and no thought was given to where the animals would move during the outage. The relief of thinking everything was back to normal caused the secondary hazard of suction on restart to be overlooked.

ImprovementAlways keep intakes and inlets covered with sponge. Set a procedure for outages: first check the animals' positions, and confirm they are away from the intake before power returns. Keep a battery-powered air pump to maintain oxygen during outages.

Night in June. One of the aeolid nudibranchs in your overflow-style saltwater tank has vanished. Searching, you find it has gone down the overflow pipe and landed on the filter wool in the sump below, moving slowly near the pump intake. Parts of the filter wool are starting to dry out.

Which is the most appropriate follow-up?

1. Drop it into the main tank at the surface and wait for it to return to the rock on its own
2. Lift out the filter wool with it, peel the animal off with your fingers and return it
3. It can live in the sump too, so leave it there and feed it
4. Stop the main pump, lift it onto a card wetted with seawater and return it to the rock in the main tank

AnswerD. Stop the main pump, lift it onto a card wetted with seawater and return it to the rock in the main tank

ExplanationThe sump has the pump intake and the filter wool dries easily, making it a dangerous place for a nudibranch. First stop the main pump to remove suction, let it climb onto a card or thin plastic sheet wetted with seawater, and return it to the rock in the main tank with minimal time in air. Peeling it off with fingers causes tears; dropping it in slams it against rock or glass and it may wash down the overflow again. The sump has no food organism and is not a place to keep it. After returning it, fit a sponge or mesh at the overflow inlet to physically prevent escapes. Make a morning head count a habit, and check the sump immediately if one is missing.

IssuesThe overflow inlet was left unblocked, leaving a setup where a nudibranch with no swimming ability would wash into the sump if it caught the current near the surface. The owner started keeping one without considering that this equipment is unsuitable for nudibranchs.

ImprovementFit a sponge or mesh on the overflow inlet and cover every intake. Understand that nudibranchs are easier to manage in a small, quiet, dedicated tank. Make a morning head count routine and set a search procedure for when one is missing.

Afternoon in March. A kitten put its paw into the lidless 10 L container in the living room, hooked out a Hypselodoris festiva and dropped it on the floor. The kitten is sniffing the nudibranch and about to take it in its mouth. The nudibranch is contracted and producing mucus but moving. Kitten toys are scattered beside the tank, and the owner has no spare container of seawater ready.

Which is the most appropriate first action?

1. Move the kitten to another room, collect the nudibranch on a card wetted with seawater and return it to a container of seawater
2. To keep the kitten from eating it, grab the nudibranch bare-handed and toss it into the tank quickly
3. Cats are fine eating sea creatures, so let the cat do as it likes
4. The nudibranch is toxic, so do not touch it; leave it on the floor until the cat goes away

AnswerA. Move the kitten to another room, collect the nudibranch on a card wetted with seawater and return it to a container of seawater

ExplanationHypselodoris festiva and similar species store defensive chemicals derived from their sponge food, and a cat that mouths one can suffer poisoning or vomiting. The correct order is to isolate the kitten in another room first, then lift the nudibranch onto a card wetted with seawater and return it to a container of seawater. Grabbing bare-handed tears it, and tossing it in slams the body. Letting the cat eat it is dangerous to both cat and nudibranch. Left on the floor, it deteriorates quickly from drying. If you suspect the cat mouthed it, call the vet and explain it may have mouthed a toxic marine mollusk. To prevent recurrence, secure the lid and keep the tank in a room the cat cannot enter.

IssuesA lidless container was placed in a room the cat uses, without considering the cat's curiosity or reach. The owner had not connected the nudibranch's toxicity to the safety of family and pets.

ImprovementKeep the tank in a room cats and small children cannot enter, secure the lid and weigh it down. Keep your vet's after-hours contact ready in case the cat mouths one. Keep seawater and a card on hand for recovery, and share the no-bare-hands rule with the family.

Low tide in May. On a family visit to a rocky shore, you found a Hypselodoris festiva and were about to take it home in a bucket. A nearby sign reads: National Park Marine Park Zone, collection of plants and animals prohibited. The bucket already holds seawater, the nudibranch and a small sponge-covered stone.

Which is the most appropriate action here?

1. One animal has little impact, so take it home anyway
2. Gently return it, stone and all, to where you found it, and limit yourself to observing and photographing
3. Return only the stone, take the nudibranch home and look for food there
4. You can always get permission at the park office, so head there with the animal

AnswerB. Gently return it, stone and all, to where you found it, and limit yourself to observing and photographing

ExplanationIn national park marine park zones, collecting designated plants and animals is prohibited or requires a permit under the Natural Parks Act, and unauthorized collection is a legal violation. Moreover, a nudibranch cannot be kept without its sponge food, so returning only the stone and taking it home guarantees starvation. The correct action is to gently return it, stone and all, to where you found it and limit yourself to observing and photographing. The reasoning that one animal is fine holds up neither legally nor biologically. There is no mechanism for obtaining a permit after the fact, and heading to the office with the animal continues the violation. Before considering any collection, check the prefectural fishery adjustment regulations, Natural Parks Act regulated zones and fishing rights in advance.

IssuesThe legal restrictions of the site were not checked before collecting, and even after seeing the sign the owner nearly rationalized that a little was fine. They acted on the assumption of taking it home without knowing about either the food problem or the legal rules.

ImprovementBefore collecting, check Natural Parks Act regulated zones, each prefecture's fishery adjustment regulations, and notices at harbors and protected areas. Enjoy observing and photographing as a rule, and keep only species whose food can be secured. Teach children to return sea creatures to where they found them.

10 a.m. on Sunday. Your 2-year-old climbed onto a stool, reached into the tank and put a Hypselodoris festiva in their mouth. The child immediately said it was bitter, spat it out and is crying. There is mucus around the mouth. The nudibranch has fallen to the floor and is contracted. The lid was only resting on the tank, not secured, and the owner is panicking, unsure who to call.

Which is the most appropriate first action?

1. Have the child rinse their mouth thoroughly with water, check what was spat out, and consult a medical provider
2. Recover the nudibranch and return it to the tank first, then watch the child until they stop crying
3. Make the child drink lots of milk to dilute the toxin and induce vomiting
4. It was only bitter and was spat out, so there is no problem; put the child down for a nap and watch

AnswerA. Have the child rinse their mouth thoroughly with water, check what was spat out, and consult a medical provider

ExplanationNudibranchs such as Hypselodoris festiva store defensive chemicals taken from their food, and swallowing one can cause poisoning. Human safety comes first: have the child rinse their mouth thoroughly with water, check what was spat out, and call a pediatrician or poison control center, explaining that the child mouthed a toxic marine mollusk. Recover the nudibranch only after the child has been attended to. Forcing vomiting with milk risks aspiration and, depending on the toxin, may speed absorption. Assuming it is fine because it was spat out and putting the child down for a nap means missing vomiting or changes in consciousness. Recover the nudibranch with a card wetted with seawater, and move the tank where the child cannot climb to it.

IssuesA toxic animal was kept at a height a toddler could reach from a stool, with an unsecured lid. The nudibranch's toxicity was not recognized as a family safety risk, and no contact for accidental ingestion had been decided.

ImprovementPlace the tank out of a toddler's reach or in another room and secure the lid. Post the poison control center and pediatrician numbers on the refrigerator. Agree as a family on the steps for ingestion: rinse the mouth, do not induce vomiting, call for advice. Consider not keeping toxic animals in a household with toddlers.

Night in June. Seeing a slight whitening on a Hypselodoris festiva's body, the owner suspected ich and added a copper-based marine ich treatment at the standard dose. Thirty minutes later, the nudibranch has fallen off the glass and is contracting violently and producing mucus. There are two other nudibranchs in the tank.

Which is the most appropriate first action?

1. The medication takes time to work, so continue for 3 days as the instructions say
2. Move all the animals, container and all, into a separate container of medication-free seawater at the same temperature and specific gravity, and do a full water change on the main tank
3. Add activated carbon to absorb the medication and leave the nudibranchs in the main tank
4. Assume the dose was too high and add fresh water to dilute it

AnswerB. Move all the animals, container and all, into a separate container of medication-free seawater at the same temperature and specific gravity, and do a full water change on the main tank

ExplanationCopper-based medications are extremely toxic to invertebrates, and nudibranchs suffer lethal damage within a short time. Ich is a fish disease; whitening in a nudibranch is body-surface damage from water quality or high temperature and not something medication treats. The top priority is getting them out of the medicated environment: move all animals, container and all, underwater into a separate container of clean seawater at the same temperature and specific gravity, then do a full water change on the main tank, add activated carbon, and do not return them until copper is no longer detectable. Continuing the treatment wipes out everything, and carbon alone takes too long to remove it. Adding fresh water throws off the gravity and adds osmotic shock. Copper also lingers in rock and sand, so consider replacing the rock.

IssuesWhitening in a nudibranch was confused with a fish disease, and medication was added without knowing its toxicity to invertebrates. The root problem was the mindset of reaching for medication instead of investigating the cause (water quality, temperature).

ImprovementDecide never to use fish medications or additives in the nudibranch tank, and store medications elsewhere. For any body-surface abnormality, first measure water quality, specific gravity and temperature to find the cause. Never reuse equipment or rock that has been exposed to medication for invertebrates.

Night in August. A family member sprayed insecticide in the room where the nudibranch tank sits, and 30 minutes have passed with the windows closed. The tank has a lid but draws in room air through the aeration. When the owner notices, the two aeolid nudibranchs have dropped to the bottom and curled up with their cerata shrunken.

Which is the most appropriate first action?

1. A large dose of activated carbon is enough, so skip the water change
2. Insecticide does not dissolve in water, so just watch until morning
3. Take the animals out bare-handed and rinse them in freshly mixed artificial seawater
4. Open the windows to ventilate, move the air pump where it can draw air from another room, and change 1/3 of the water with seawater at the same temperature and specific gravity

AnswerD. Open the windows to ventilate, move the air pump where it can draw air from another room, and change 1/3 of the water with seawater at the same temperature and specific gravity

ExplanationInsecticide components dissolve into the water through aeration and the surface and are especially toxic to invertebrates. First ventilate to lower the concentration in the room, relocate the air pump so it does not pump contaminated air into the water, and change 1/3 of the water with seawater at the same temperature and specific gravity to lower the concentration in the tank. Adding activated carbon helps but is no substitute for a water change. The claim that it does not dissolve is wrong; leaving it makes things worse. Taking them out bare-handed risks tears and stings, and rinsing in freshly mixed seawater is another sudden change. After the water change, keep it dark and quiet and observe without touching until morning. Agree with the family never to use insecticide in the room with the tank.

IssuesThe family did not understand that the tank was there or that insecticide was dangerous, and sprayed in a closed room. The owner had not recognized that the air pump sends room air directly into the water.

ImprovementAgree as a whole family never to use insecticides, air fresheners or foggers in the room with the tank, and post a notice. Control mosquitoes with screens and the lid. Extend the air pump's intake to another room or a window, and keep emergency water-change seawater in stock.

1 p.m. in August. Lightning caused an outage, stopping the aquarium chiller and air pump. It is 35°C outside, the room keeps warming, and the 20 L tank has gone from 20°C to 23°C in 30 minutes. It holds two Hypselodoris festiva collected from a temperate shore. There is no estimate for when power will return. There are several ice packs in the freezer.

Which is the most appropriate first response?

1. Put the nudibranchs in the refrigerator's vegetable drawer to keep them cool
2. Put ice from the freezer directly into the water to get back to 20°C quickly
3. Float ice packs in bags, run a battery-powered air pump, and log the water temperature every hour
4. Dump all the tank water and replace it with seawater mixed from cold tap water

AnswerC. Float ice packs in bags, run a battery-powered air pump, and log the water temperature every hour

ExplanationDuring an outage, the priorities are slowing the temperature rise and securing oxygen. Floating ice packs in bags cools gradually without changing the gravity, and a battery-powered air pump supplies oxygen. Hourly temperature logging tracks the rate of rise; add more ice packs if it looks set to exceed 25°C. Ice placed directly in the water melts and lowers the gravity, and localized rapid chilling stacks osmotic and temperature shock. The refrigerator is lethal through dry air and rapid cooling. A full water change causes sudden temperature and gravity changes and is unrealistic without dechlorination and preparation. After power returns, also watch for a sharp temperature drop when the chiller restarts.

IssuesNo backup was prepared for a summer outage stopping the chiller; there was neither a battery-powered air pump nor bagged ice packs. Awareness that a few hours of high temperature is fatal to temperate species was weak.

ImprovementKeep a battery-powered air pump, several ice packs in sealed bags and a styrofoam box on hand, and write out the outage procedure. Keep the tank in an air-conditioned room in summer, set an upper temperature limit and act immediately when exceeded. If a long outage is expected, keep the option of returning them to the sea.

2 a.m. A strong earthquake knocked the 15 L tank off the shelf and it shattered, scattering seawater, rock and three Hypselodoris festiva across the floor. The family is unharmed, and aftershocks continue. The nudibranchs are each contracted on the floor. You have 10 L of pre-mixed artificial seawater, a bucket and plastic containers.

Which is the most appropriate first action?

1. First secure your own and your family's safety; once things settle, collect the animals on a wetted card into a container of seawater
2. Before the next aftershock, grab them all bare-handed and put them in a bucket of tap water
3. Search for the animals among the broken glass and lift them out together with the tank fragments
4. Gather the rock and sand first and set up a new tank before collecting the nudibranchs

AnswerA. First secure your own and your family's safety; once things settle, collect the animals on a wetted card into a container of seawater

ExplanationIn a disaster, human safety comes first; broken glass and a wet floor pose a risk of falls and injury. Once safe, prepare a container of artificial seawater and collect each animal on a card or thin plastic sheet wetted with seawater. Grabbing bare-handed causes tears and stings to your hand, and tap water is nearly instantly fatal. Lifting them with glass fragments leads to human injury. Setting up a new tank comes later; keep the collected animals in a dark, quiet container with a battery-powered air pump. If a stable environment cannot be provided for the survivors, consider returning them to the collection site.

IssuesThe tank was placed on a shelf without being secured, with no earthquake precautions. The owner lacked both the priority order of human safety over animal recovery, and the stock of seawater and tools needed for recovery.

ImprovementPlace the tank on a low, stable stand secured with anti-tip mats and straps. Store pre-mixed artificial seawater, a battery-powered air pump, plastic containers and cards with your disaster supplies. Assume you cannot take nudibranchs when evacuating, and set criteria in advance for returning them to the collection site.

Morning in January. In a 10 L tank housing a tropical aeolid nudibranch collected from a southern sea, the water fell from 26°C to 18°C overnight because the room heating was switched off at bedtime. No aquarium heater is installed. The nudibranch sits motionless on the rock with its cerata deflated. For several days the pattern has been the water warming back to 26°C with the daytime heating.

Which is the most appropriate response to this situation?

1. Turn the room heating to maximum and get back to 26°C quickly during the morning
2. Install a guarded aquarium heater, bring it back at 1–2°C per hour, and keep the temperature constant from then on
3. Even tropical species acclimate to cold in winter, so continue as is
4. Pour in hot water to warm it back up quickly

AnswerB. Install a guarded aquarium heater, bring it back at 1–2°C per hour, and keep the temperature constant from then on

ExplanationNudibranchs are ectotherms, and an environment that swings 8°C every day places a severe burden on metabolism and immunity, leading to body-surface breakdown and weakening. Tropical species need a heater to keep a constant temperature: install a guarded one, bring the water back gradually at 1–2°C per hour, and then hold it stable around 24–26°C. Rapid heating with the room heater or pouring in hot water causes osmotic shock through sudden temperature and gravity changes. Tropical species never acclimate to cold; continued 18°C is fatal. The proper premise is to check the collection-site water temperature and not keep the animal unless you have equipment to maintain it year-round.

IssuesThe collection-site water temperature was not checked, and a tropical species was kept in winter relying on room temperature. The owner did not understand the strain large day-night swings put on the animal and had no heater ready.

ImprovementCheck the water temperature at the collection site or supplier and keep it constant year-round with a heater and thermostat. Log the daily range with a max-min thermometer and fix any setup that swings 3°C or more. Use a guarded heater to prevent pinching accidents.

Morning in July. Yesterday you collected nudibranchs on the shore, cut a fingertip on a rock, and then did a water change bare-handed with the cut still open. This morning the area around the cut is red, swollen and hot, and the finger is painful and hard to bend. The owner is under treatment for a chronic liver condition. Gloves were available but not used because they were a hassle. The swelling has clearly spread since last night.

Which is the most appropriate follow-up?

1. Apply an over-the-counter ointment and watch for a few days until the swelling goes down
2. The nudibranch's toxin is the cause, so getting rid of the nudibranch will cure it
3. Seawater is antibacterial, so wash the wound with tank water
4. See a medical provider the same day and tell them the wound was exposed to seawater and about the chronic condition

AnswerD. See a medical provider the same day and tell them the wound was exposed to seawater and about the chronic condition

ExplanationWounds from seawater or shore rocks can be invaded by marine bacteria such as Vibrio vulnificus, causing rapidly progressing infections, and people with liver disease are prone to severe illness. Red, swollen, hot and intensely painful skin requires a same-day medical visit; be sure to mention that the wound was exposed to seawater and the chronic condition. Watching with an OTC ointment means missing the progression, and washing with seawater drives more bacteria into the wound. Nudibranch toxins can cause dermatitis or poisoning, but this course points to bacterial infection, and getting rid of the animal solves nothing. From now on, never put a hand with a cut into seawater.

IssuesThe owner collected on the shore and worked in the tank with a cut hand, unaware of the risk of marine bacterial wound infection. Despite a liver condition that predisposes to severe illness, neither gloves nor wound protection were used.

ImprovementAlways wear gloves for shore collecting and tank work, and do not work on days you have a cut. Wash hands with soap afterward. If a seawater-exposed wound swells, see a doctor without waiting and mention the chronic condition. People with liver disease or weakened immunity should think carefully about keeping marine animals at all.

Midday in May. Trying to move a collected aeolid nudibranch off the rock bare-handed, you felt a sharp pain in your fingertip, and a few minutes later a red welt appeared and it stings. You are standing at the faucet about to wash it. The nudibranch is back in the tank. There is a bowl of seawater beside the tank, but the owner is thinking of scrubbing hard with fresh water first.

Which is the most appropriate treatment for the finger?

1. Rinse with seawater, cool without rubbing, and watch whether the swelling spreads
2. Scrub hard with fresh water to remove the stinging cells
3. Suck out the venom with your mouth
4. Heat breaks down the venom, so soak it in hot water

AnswerA. Rinse with seawater, cool without rubbing, and watch whether the swelling spreads

ExplanationAeolid nudibranchs take stinging cells from the hydroids and anemones they eat and store them in their cerata for defense. Touching one bare-handed fires the stinging cells, causing pain and welts. Treatment is to rinse with seawater to remove remaining stinging cells, cool without rubbing, and watch whether the swelling spreads. Fresh water and scrubbing stimulate remaining stinging cells and trigger more firing. Sucking with the mouth puts stinging cells on the oral mucosa, and hot water can backfire depending on the type of stinging cell and risks a burn. Seek medical care immediately if swelling spreads or numbness, hives or breathing discomfort appear. From now on, never touch nudibranchs, especially aeolids, bare-handed.

IssuesThe owner did not know that aeolid nudibranchs store stinging cells and can sting, and tried to peel one off the rock bare-handed. There was also a knowledge gap in that only counterproductive treatments like fresh water or sucking came to mind.

ImprovementAlways wear gloves for tank work and move animals by letting them climb on with a container and card. Post the sting procedure: rinse with seawater, do not rub, cool, see a doctor if it worsens. Check a field guide for species that may carry stinging cells.

11 p.m. in April. The Hypselodoris festiva in your 20 L tank has dropped to the bottom and curled up, with rhinophores and gills retracted, and has not moved for 30 minutes. The color is unchanged and there is no melting or odor. The owner thinks it is dead and is debating whether to take it out and throw it away. Specific gravity 1.024, temperature 19°C, ammonia zero.

Which is the most appropriate way to check whether it is alive?

1. Pick it up by hand and check its weight and firmness
2. Gently puff seawater at it with a pipette and watch whether the rhinophores or body contract even slightly
3. Take it out of the water for 30 seconds and see whether it moves
4. If it does not move it is dead, so remove and discard it immediately

AnswerB. Gently puff seawater at it with a pipette and watch whether the rhinophores or body contract even slightly

ExplanationWhen startled or when conditions change, nudibranchs retract their rhinophores and gills, let go of the glass and may stay still for a long time; not moving does not mean dead. To check, apply a weak stimulus such as a gentle puff of seawater from a pipette and watch whether the rhinophores or body contract even slightly. If they contract, it is alive. Picking it up causes tears, and taking it out of the water weakens it through drying. Death is judged by signs such as the body starting to melt, a foul smell, or no response to stimulus with loss of body firmness. If water quality is normal, dim the lights and observe without touching until morning; if it still has not moved the next day, suspect lack of food or damage during collection.

IssuesThe owner did not know that nudibranchs contract and stay still for long periods after a stimulus, and equated stillness with death. Considering disposal without any method to confirm survival showed risky judgment.

ImprovementDecide to confirm survival by whether it contracts when seawater is puffed at it and whether its position has changed by morning, and to judge death by three signs: melting, foul smell and no response. Make a habit of dimming the lights and waiting until morning for animals that are still at night.

Morning in June. After two weeks of keeping, a Hypselodoris festiva has begun to shrink, so you decide to return it to the collection site an hour away by car. It is 28°C outside. The owner is about to put the nudibranch in a small sealed container filled only halfway with water, close the lid, and set it in the sun on the passenger seat.

Which is the most appropriate transport method?

1. Fill the container completely with seawater leaving no air, place it in a styrofoam box with ice packs, and keep it dark
2. Leave the water at half and plenty of air for oxygen, and set it on the passenger seat so it does not shake
3. Wrap it in wet tissue and carry it without water so it does not dry out
4. Put it in a bucket with the tank water and drive with the window open so the breeze hits it

AnswerA. Fill the container completely with seawater leaving no air, place it in a styrofoam box with ice packs, and keep it dark

ExplanationWhen transporting a nudibranch, any air left in the container lets shaking expose the body to air or slam it against the surface, so the basic rule is to fill it completely with seawater with no air. Water temperature must be kept the same as the collection site, so place it in a styrofoam box with bagged ice packs and carry it dark and without shaking. For a short trip, dissolved oxygen is sufficient, and the harm from shaking outweighs any benefit of air space. Wrapping in tissue is fatal through drying and tears. A bucket in the breeze lets the temperature swing and the sloshing water injures the body. On arrival, check the difference between the container water and the sea temperature at the exact collection spot, then gently release it in the shade of a rock.

IssuesThinking like fish transport, the owner planned to leave air space, without considering that a shell-less body is injured by shaking or that a car interior gets hot in summer. The decision to return it was right, but knowledge of the transport procedure was lacking.

ImprovementKeep a sealed container, styrofoam box and bagged ice packs ready for transport. Write out the procedure: fill with seawater, keep dark, match the collection-site temperature, do not shake. Record the exact collection point and release it on the same rocks.

Night in May. Two Hypselodoris festiva, collected three weeks ago together with their sponge, have laid a white ribbon-shaped egg mass on the side of the rock. Since the next day, one has not returned to the food and sits contracted on the bottom, sluggish. Water quality, specific gravity and temperature have been stable since collection. The owner suspects illness and is wondering whether to add some medication.

Which is the most appropriate understanding and response?

1. Weakening after spawning is a natural course near the end of life; use no medication, leave it quietly, and observe the egg mass without removing it
2. It lost calcium in spawning, so add an extra dose of coral calcium supplement
3. The eggs will foul the water, so scrape off the egg mass, isolate the parent and give it a medicated bath
4. The weakening is from lack of food, so force frozen food against its mouth

AnswerA. Weakening after spawning is a natural course near the end of life; use no medication, leave it quietly, and observe the egg mass without removing it

ExplanationMost nudibranchs live a few months to under a year, and after spawning they soon weaken and reach the end of their lives. With stable water and food, slowing down after spawning is a natural course that medication or additives cannot change. Overdosing calcium supplements throws off the water chemistry. There is no need to scrape off the egg mass; it can be left for observation. Hypselodoris festiva larvae cannot be raised in captivity, so there is no worry about eggs overrunning the tank. It will not eat frozen food, and pressing food against its mouth injures the body. Keep up water management for the remaining animal, and remove any dead animal before it melts to protect the water.

IssuesThe owner did not know how short a nudibranch's life is or that spawning comes near the end of it, and mistook natural decline for illness. The impulse to solve it with medication or additives risked harming the remaining animal as well.

ImprovementBefore keeping, research the species' lifespan and reproductive cycle and understand that weakening after spawning is natural. Remove dead animals early through daily observation to protect water quality. Given how short-lived they are, collect the minimum number and preferably limit yourself to observing and photographing.

Morning in June. In a 15 L tank housing two Hypselodoris festiva collected a week ago, the surface of the sponge-covered stone you brought home with them has turned black and slimy, and the water gives off a rotten smell unlike the usual sea smell. The nudibranchs have left the stone and are on the glass, but their rhinophores are out. Ammonia tests clearly positive.

Which is the most appropriate first action?

1. The sponge is their only food, so leave the stone in place, rotten parts and all
2. Remove the stone with the decaying sponge and change 1/3 of the water with seawater at the same temperature and specific gravity to restore water quality
3. Place the nudibranchs back on the stone by hand so they eat it before it rots
4. Adding powerful filter media will stop the sponge rotting, so skip the water change

AnswerB. Remove the stone with the decaying sponge and change 1/3 of the water with seawater at the same temperature and specific gravity to restore water quality

ExplanationSponges die easily in a tank and, once decaying, become a powerful ammonia source that fouls the water quickly. The nudibranchs leaving the stone on their own is a behavior to avoid the decay. The priority is to remove the stone that is the source of decay and change 1/3 of the water with seawater at the same temperature and specific gravity to restore water quality. Leaving rotten food poisons every animal, and placing them back by hand causes tears. Adding filter media does not stop decay and cannot keep up with an ammonia spike. Once the food is gone, continued keeping becomes difficult, so unless you can secure a new food organism, decide to return them to the collection site while they still have strength.

IssuesThe owner did not know that sponges do not live long in a tank and did not anticipate that food decay is the biggest cause of water-quality collapse. There was also no habit of checking the food's condition daily.

ImprovementCheck the food organism's color, shape and smell daily and remove it immediately if it blackens or breaks down. Plan from the outset to return the animals when the food runs out. Test ammonia daily and always keep water-change seawater in stock.

Sunday afternoon. At a marine fish shop, brightly colored nudibranchs are on sale labeled as algae eaters. Asked about food, the clerk gives a vague answer that they eat algae and microorganisms in the tank. No species name is shown. You have a marine fish tank at home and are inclined to take one home.

Which is the most appropriate decision here?

1. It is beautiful, so buy it and look up its food in a field guide at home
2. The clerk says it eats, so trust that, buy it and add it as an algae eater
3. Since the species and food organism are unclear and there is no prospect of securing food, do not buy it
4. Buy one for now, and if it starves try a different species

AnswerC. Since the species and food organism are unclear and there is no prospect of securing food, do not buy it

ExplanationMost nudibranchs eat only specific sponges, hydroids, bryozoans and the like, and almost all of those sold as eating algae and microorganisms starve in captivity. Buying an animal with no species name, no known food organism and no prospect of securing food means starving it within weeks. Buying first and researching later, or trying one to see, only cuts short an already short-lived animal. These are not the same as true algae-eating snails (such as turban snails); placed in a fish tank they find no food and get picked at and injured by the fish. Buy only when the species is identified and you have confirmed you can continuously supply its food.

IssuesThe owner nearly decided impulsively on appearance and skipped the minimum research of confirming species and food organism. Taking the seller's vague explanation at face value was also a classic path to starvation.

ImprovementAlways confirm the species name before buying and research its food organism and how to obtain it specifically. As a rule, never buy nudibranchs labeled as algae eaters. Satisfy the urge to keep one at aquariums or tide-pooling, and buy a live animal only when its food can be secured.

Night in May. You are keeping an aeolid nudibranch, collected together with its hydroid-covered rock, in a 10 L container. Today you moved the container to another room and switched to a stronger light, after which several cerata dropped off its back onto the bottom and the animal contracted in the shade of the rock. The dropped cerata kept moving for a while. Water quality and specific gravity are normal.

Which is the most appropriate understanding and response?

1. The cerata are being eaten by parasites, so remove the remaining ones with tweezers
2. This is most likely autotomy from severe stress; dim the lights, keep it quiet and observe without touching
3. Losing cerata is a disease, so add fish medication at the standard dose
4. To restore them, line up the dropped cerata next to the body with tweezers

AnswerB. This is most likely autotomy from severe stress; dim the lights, keep it quiet and observe without touching

ExplanationAeolid nudibranchs shed their cerata on their own to protect themselves when subjected to strong stimulus or stress, and dropped cerata moving for a while is characteristic of this. The environmental change of moving the container and the stronger light is the likely trigger; the response is to dim the lights, keep it dark and quiet, and observe without touching. Cerata can regenerate over time. Assuming parasites and removing the rest with tweezers is fatal, and fish medication is harmful to invertebrates. Dropped cerata cannot be reattached, and bringing them near the body with tweezers is another stimulus. If cerata keep dropping and the body shrinks after several days, suspect lack of food or collection damage and consider returning it.

IssuesThe owner underestimated the effect of environmental change on nudibranchs and changed location and lighting on the same day. Not knowing that aeolids autotomize, they misread it as disease or parasites and nearly intervened.

ImprovementChange only one thing at a time, and keep lighting dim, just enough not to harm the hydroid food. Do not move the container; observe through the glass. Understand that aeolids carry stinging cells and autotomize, and strictly follow the no-touching rule.

Night in July. Because the water level in the 8 L container had dropped, the owner poured in 1 L of dechlorinated fresh water all at once. Ten minutes later, the Hypselodoris festiva's body has swollen as if waterlogged, and it has fallen off the glass and lies motionless on the bottom. Specific gravity has dropped to 1.019. Beside the container is a stock of artificial seawater at 1.024.

Which is the most appropriate follow-up?

1. Replace all the water right now with the 1.024 seawater to restore the original concentration
2. Add salt directly to the container to quickly raise the gravity to 1.024
3. Gently move the animal to a separate container of 1.024 seawater, and bring the main container's gravity back over several days
4. The swelling is temporary, so leave it and re-measure gravity tomorrow

AnswerC. Gently move the animal to a separate container of 1.024 seawater, and bring the main container's gravity back over several days

ExplanationAdding a large amount of fresh water at once to a small container dropped the gravity sharply, and water is flooding into the shell-less body in osmotic shock. Abruptly returning an animal that has already suffered a sudden change to the original concentration stacks a second shock in the opposite direction. The realistic best option is to gently move the animal, container and all, underwater into a separate container of 1.024 seawater to give it a stable environment, and to bring the main container's gravity back over several days by stopping fresh-water additions. A sudden full change or adding salt directly changes gravity all at once, and dissolving salt touching the body is fatal. Leaving it means prolonged low gravity leading to body-surface breakdown. After moving it, keep it dark and untouched and observe until morning.

IssuesThe owner had not calculated that adding a full liter of fresh water to only 8 L would shift the gravity significantly. They lacked both the principle of topping up in small amounts and the knowledge that sudden gravity changes are fatal to nudibranchs.

ImprovementTop up in small amounts, a few percent of the volume at most per addition, in several steps, measuring gravity each time. Mark a water line on the container and top up a little every day. Increase water volume to reduce gravity swings, and keep the hydrometer within reach to make checking a habit.

Evening in June. Two weeks after collection, the tips of an aeolid nudibranch's cerata have gone from the vivid orange they were at collection to whitish. The body is also a little smaller. The hydroids collected with it have died off and almost nothing remains. Water quality is normal; the owner thinks the lighting is too dim and is about to increase it.

Which is the most appropriate explanation and response for this change?

1. The hydroid food is gone, so it has lost the source of its color and is heading toward starvation; return it if food cannot be re-secured
2. This is fading from lack of light, so use a strong coral light
3. Fading is natural aging, so just keep going
4. To replace the pigment, dissolve a food with coloring agents in the tank

AnswerA. The hydroid food is gone, so it has lost the source of its color and is heading toward starvation; return it if food cannot be re-secured

ExplanationMuch of a nudibranch's vivid coloration comes from pigments or symbiotic algae taken from its food, and the color fades when food runs out. A shrinking body and whitening color with the hydroid food dead is the typical course toward starvation. The response is to re-secure the food organism; if there is no prospect of that, return it to the collection site while it still has strength. Lighting is not the cause of coloration, and strong light further damages the hydroids and raises the temperature. Assuming aging and continuing means starving it. It will not eat coloring agents or artificial food, which only foul the water. The premise is to check remaining food daily and plan to secure the next food or return the animal before it runs out.

IssuesDespite seeing that the food organism had died, the owner misattributed the color change to lighting. They lacked the perspective of linking remaining food to the animal's condition, and had no plan to return it once the food ran out.

ImprovementObserve remaining food daily and decide to re-collect or return when it drops below half. Photograph body color, length and rhinophore condition and compare with collection. Since hydroids do not last long in a tank, limit keeping aeolids to short-term observation.

Afternoon in May. You put a Hypselodoris festiva collected on the shore in a plastic bag half filled with seawater, along with a stone, and drove two hours home. On opening the bag, the edge of its body has been torn on the corner of the stone, and it is covered in mucus near the water surface in the bag. The rhinophores move slightly. The owner is about to hurry it into the tank.

Which is the most appropriate first action?

1. Pour the bag water and all into the tank and let the pump flow wash off the mucus
2. Take it out of the bag with your fingers, press the torn part closed and stick it onto the tank rock
3. A torn animal cannot be saved, so discard it with the bag
4. Check the temperature difference between the bag and the tank, then gently transfer it, bag water and all, into a separate resting container of seawater

AnswerD. Check the temperature difference between the bag and the tank, then gently transfer it, bag water and all, into a separate resting container of seawater

ExplanationPutting a stone in the same bag for a long drive lets the body strike the stone's corners with every jolt, causing tears. The best thing for a torn animal is to rest in clean seawater with no flow: check the temperature difference between the bag and the tank, equalize it, then gently transfer it, bag water and all, into a separate resting container of seawater. Pump flow widens the tear, and pinching or pressing with fingers tears it further. Small tears are sometimes covered by mucus and recover, so discarding an animal whose rhinophores still move is premature. Proper transport is a container filled completely with seawater holding only the animal, the stone in a separate container, and ice packs to hold the temperature.

IssuesPutting the stone and the animal in the same bag, with air left in, and shaking it during transport caused the tear. On arrival, the rush to get it into the tank nearly skipped the basic steps of temperature matching and resting.

ImprovementTransport the animal and the stone in separate containers, filled completely with seawater and no air, in a dark styrofoam box with ice packs. After getting home, match the temperature before transferring to a resting container, observe for half a day, then move it to the main tank. Keep what you bring home from collecting to a minimum.

Night in April. Seeing something like a bit of lint on a Hypselodoris festiva's back, the owner tried to remove it with tweezers, pinched the body surface and tore it slightly. The nudibranch contracted violently and mucus is oozing from the tear. The owner is about to try removing the lint with tweezers again.

Which is the most appropriate follow-up?

1. Lint is bad for it, so this time carefully remove it completely with tweezers
2. Stop touching it, leave it, rock and all, to rest in a separate container of clean seawater with no flow, and observe until the next day
3. Germs could enter the wound, so add a fish disinfectant to the tank
4. Take it out into the air for a while to dry the wound

AnswerB. Stop touching it, leave it, rock and all, to rest in a separate container of clean seawater with no flow, and observe until the next day

ExplanationA nudibranch's body surface is extremely soft, and pinching it with tweezers alone tears it. Lint and other debris usually come off naturally with the mucus, and trying again only widens the wound. The correct response is to stop touching it, move it together with the rock to a separate container of clean seawater with no flow, and observe until the next day. Fish disinfectants are harmful to invertebrates, and exposure to air is fatal through drying. Small tears can be covered by mucus and recover, but if melting begins, keep it isolated to protect the main tank. Even when a white attachment on the body is a parasite's egg sac, do not remove it, since pulling tears the body.

IssuesThe owner did not know the rule that any care touching the body is forbidden, and tried to remove what looked like dirt. Even after failing, they were about to repeat the same action, unable to make the decision not to touch.

ImprovementDecide that tweezers and nets are never used in the nudibranch tank, and store the tools elsewhere. Only observe anything attached to the body; siphon feces and mucus from around it with a pipette. Post the rules: do not touch, do not peel, do not dry.

Low tide in May. You found a Hypselodoris festiva on the shore and tried to pull it off the rock with your fingers; it was clinging tightly, the edge of the body tore and a piece stayed on the rock. The nudibranch is contracted in your palm. Collecting is not restricted here, and there is no sponge food in sight nearby.

Which is the most appropriate follow-up?

1. Take the injured animal home and treat it there
2. Gently return it to the tide pool at the original rock and do not touch it further
3. Press the torn piece back onto the body and stick it to the rock
4. Wrap it in a wet towel so it does not dry out and take it home

AnswerB. Gently return it to the tide pool at the original rock and do not touch it further

ExplanationPulling a nudibranch off a rock with fingers is the most common cause of tears, and there is no way to treat it at home. With no sponge food in sight, keeping it is not viable, and taking an injured animal home kills it through both starvation and the tear. The correct response is to gently return it, underwater, to the tide pool at the original rock and not touch it further. Small tears get covered by mucus and may recover in the natural environment. Pressing the torn piece back will not reattach it, and a towel is fatal through drying and friction. A nudibranch clinging to rock should never be pried off; wait for it to move on its own, or limit yourself to observing and photographing.

IssuesThe owner did not confirm the presence of food before collecting and used the most dangerous method, pulling a clinging animal off with fingers. They did not understand that the idea of taking an injured animal home to help it actually leads to its death.

ImprovementOn the shore, never pry off a clinging animal; make observing and photographing the rule. If you do collect, take an animal sitting on its food, food and all, by scooping it underwater in a container. Understand that returning an injured animal to its spot is best, and collect only when truly necessary.

Late night in June. For a week you have kept two small hermit crabs and one Hypselodoris festiva, collected from the shore, in the same 10 L container. Turning on the light in the night, you find a hermit crab gripping the edge of the nudibranch's body in its claw and dragging it. The nudibranch is contracted and part of its edge is torn off. The other hermit crab is approaching too.

Which is the most appropriate first action?

1. Immediately move both hermit crabs to another container, and leave the nudibranch untouched in the dark to rest
2. Pinch the nudibranch with your fingers and move it to the rock near the surface for safety
3. Feeding the hermit crabs will fill them up so they stop attacking, so add plenty of food
4. Hermit crabs attack only at night, so keep the light on at night

AnswerA. Immediately move both hermit crabs to another container, and leave the nudibranch untouched in the dark to rest

ExplanationHermit crabs and crabs are omnivores that attack and eat slow-moving nudibranchs at night. The correct response is to move the attackers, the hermit crabs, to another container immediately and leave the injured nudibranch untouched in the dark to rest. Pinching the nudibranch tears it further. Extra food does not stop predation and fouls the water, causing secondary harm. Keeping the light on stresses the nudibranch, and hermit crabs attack by day too. A torn edge can be covered by mucus and recover, but if melting begins the next day, keep it isolated. The basic rule is to keep nudibranchs alone or with the same species only, never with predators.

IssuesThe owner did not know that hermit crabs are omnivores that prey on nudibranchs, and housed them together in a small container. The assumption that animals collected together from the shore can coexist led to the nighttime attack.

ImprovementMake solitary keeping the rule for nudibranchs and never house them with crabs, hermit crabs or fish. Collect the minimum number of animals and prepare a separate container for each species. Understand that a preyed-upon animal has a poor chance of recovery and keep the option of returning it early.

Evening in September. An hour after adding a Hypselodoris festiva to your marine fish tank, the wrasses and damselfish are picking at its gill plume and rhinophores; the gill tips are torn and shrunken. The nudibranch is trying to escape behind the rock. The owner figures they will get used to it eventually.

Which is the most appropriate first action?

1. Fish learn to avoid toxic animals and will stop attacking, so just observe
2. Give the fish extra food to distract them and let the nudibranch stay behind the rock
3. Lift it out, rock and all, in a container underwater, move it to a separate quiet container, and never put it in the fish tank again
4. Scoop the nudibranch up with a net, move it to the other side of the tank and add a divider

AnswerC. Lift it out, rock and all, in a container underwater, move it to a separate quiet container, and never put it in the fish tank again

ExplanationFish in a marine tank, especially wrasses and damselfish, pick at the gills and rhinophores of slow-moving nudibranchs and inflict fatal injuries in a short time. A nudibranch's toxins do not act fast enough to count on fish learning; it loses its gills while being picked at. The correct response is to lift it out, rock and all, in a container underwater, move it to a quiet container with no fish, and never put it in the fish tank again. Distracting with food is temporary and fouls the water. Scooping with a net causes tears, and small fish pass through dividers. After moving it, keep it dark and untouched and observe until the next day. It may survive partial gill loss through skin respiration, but if melting begins, keep it isolated.

IssuesThe nudibranch was put in the fish tank as decoration or an algae eater without considering that fish are predators. The expectation that they would get used to it nearly led to neglect that would have worsened the injuries.

ImprovementKeep nudibranchs alone in a dedicated small container with no fish or crabs. Understand that putting one in a fish tank fails on both food and safety grounds. Decide to move animals with a container and card, never a net.

Morning in April. The Hypselodoris festiva in your 10 L tank is missing; searching, you find it contracted on the floor behind the tank stand. It apparently crawled out through the hole in the lid for the air tubing and fell. The body is somewhat shrunken and covered in mucus but still moist. It moves slightly when touched. You have a spare container of seawater on hand.

Which is the most appropriate recovery and prevention response?

1. Lift it onto a card wetted with seawater, return it to the spare container, plug the hole with sponge and lower the water level
2. Pick it up with your fingers and toss it into the tank, and seal the hole completely with tape to block the air
3. An animal that has fallen once will never recover, so go collect a new one
4. Rinse it with tap water to wash off the floor dirt before returning it to the tank

AnswerA. Lift it onto a card wetted with seawater, return it to the spare container, plug the hole with sponge and lower the water level

ExplanationNudibranchs climb the glass and crawl out through the smallest gaps or cable holes and fall. Recover it by lifting it onto a card or thin plastic sheet wetted with seawater, returning it to a container of seawater, and waiting for recovery without touching it. Picking it up with fingers causes tears, and tossing it in slams the body. Tap water is fatal through chlorine and the osmotic effect of fresh water. Prevent recurrence by plugging the cable hole with sponge and keeping the water level 5 cm or more below the rim. Sealing completely with tape stops oxygen exchange at the surface and causes suffocation. Fallen animals usually recover, and before collecting a new one you should first fix the flaws in the current setup. Observe for half a day after recovery and return it to the main tank if there is no melting.

IssuesThe owner underestimated the habit of crawling out over the waterline, left the cable hole open and kept the water level high. With no morning head count, the fall went unnoticed for a long time.

ImprovementPlug the cable holes in the lid with sponge and keep the water level 5 cm or more below the rim. Check each animal's position and count every morning and before bed. Keep seawater and a card beside the tank for recovery and tell the family the recovery procedure.

Midday in July. You left a bucket holding two Hypselodoris festiva and a sponge-covered stone collected on the shore in the car in the blazing sun for about 40 minutes over lunch. On returning, the bucket water is warm, the nudibranchs are curled up near the surface, and one is trailing strands of mucus. The sea is a 5-minute walk away.

Which is the most appropriate action here?

1. Take them the 2 hours home and let them recover in the chilled tank
2. Put convenience-store ice directly in the bucket to chill it quickly, then take them home
3. Slowly add seawater to narrow the temperature gap, then return both to where they were collected
4. Discard the one trailing mucus and take only the healthy one home

AnswerC. Slowly add seawater to narrow the temperature gap, then return both to where they were collected

ExplanationBucket water left 40 minutes in a car in the sun far exceeds the shore temperature and reaches lethal levels. The animal trailing mucus has begun to break down from heat damage and cannot survive a 2-hour trip. The best chance of survival is to slowly add seawater to narrow the temperature gap and return them immediately to where they were collected. Ice placed directly in the water lowers the gravity and stacks osmotic and temperature shock from rapid chilling. Discarding a weakened animal is premature; it may recover once back in the sea. The basic rule while collecting is to keep the bucket in the shade with bagged ice packs to hold the temperature; leaving animals unattended over lunch is itself the cause of the accident.

IssuesThe owner did not consider that a car interior in summer becomes lethally hot within minutes and that the water in a small bucket changes temperature rapidly with the air. Leaving animals unattended during collection nearly killed them before keeping even began.

ImprovementBring a styrofoam box with ice packs when collecting and never leave animals in the car. Collect just before heading home and keep the number to a minimum. Decide in advance that weakened animals are returned on the spot rather than taken home.

Night in August. The live rock stacked in your 20 L tank has collapsed, trapping an aeolid nudibranch between the rock and the bottom. Part of its body is visible under the rock and its cerata are shrunken. The owner is about to lift the rock bare-handed. The rock is fist-sized and there is room to move it inside the tank.

Which is the most appropriate first action?

1. Put on gloves, lift the rock gently underwater and set it elsewhere, then leave the animal untouched and wait for it to move on its own
2. Lift the rock bare-handed while pinching the nudibranch with your fingers to pull it out
3. Moving the rock could collapse the others, so wait for the nudibranch to free itself
4. Lift the rock straight out of the tank and remove the nudibranch with dry hands

AnswerA. Put on gloves, lift the rock gently underwater and set it elsewhere, then leave the animal untouched and wait for it to move on its own

ExplanationA nudibranch pinned under rock tears if pulled. The correct response is to put on gloves, lift the rock gently underwater and set it elsewhere, then leave the animal untouched and wait for it to move on its own. Aeolids carry stinging cells, so bare hands get stung, and pinching it out causes tears. Waiting for it to free itself means continued crushing and tissue breakdown, and lifting the rock out of the tank exposes aquatic life to air. After the rescue, reduce flow, keep it dark and observe until the next day; isolate if melting begins. To prevent recurrence, place rock directly on the tank bottom for a stable base and avoid stacking, or fix it with adhesive.

IssuesRock was stacked without securing it, and the owner did not anticipate that the nudibranch could not escape a collapse. Working bare-handed in an emergency and nearly deciding to pull the animal out was also dangerous.

ImprovementPlace rock directly on the bottom for stability, and if stacking, fix it with aquarium-safe adhesive. Leave no gaps between rock and glass or rock and rock that the body can get into. Wear gloves for tank work and follow the steps: cut power, move the equipment, do not touch the animal.

Sunday midday. Your school-age child, saying the water had gone down, poured three cups of tap water into the 8 L tank. Ten minutes later, the two Hypselodoris festiva have fallen off the glass and are swollen on the bottom with rhinophores retracted. Specific gravity has dropped to 1.020 and there is chlorine in the water. You have artificial seawater at 1.024 at the same temperature on hand.

Which is the most appropriate first action?

1. Add salt to the tank to restore the specific gravity
2. Add a dechlorinator and bring the gravity back over several days as is
3. Move the animals, container and all, underwater into a separate container of 1.024 seawater, and bring the main tank back slowly
4. Scold the child and watch the nudibranchs until morning

AnswerC. Move the animals, container and all, underwater into a separate container of 1.024 seawater, and bring the main tank back slowly

ExplanationA large addition of tap water causes chlorine toxicity and osmotic shock from a sudden gravity drop at the same time. Leaving the animals in a chlorinated main tank is itself dangerous, so the best option is to gently move them, container and all, underwater into a separate container of 1.024 seawater at the same temperature. Bring the main tank back slowly with dechlorinator and water changes, and return the animals once it has settled. Adding salt directly is fatal when half-dissolved salt touches the body, and adds a sudden gravity swing. A dechlorinator does not fix the low gravity, and the animals keep suffering. Leaving them until morning leads to body-surface breakdown. Rather than scolding, explain to the child the rule not to touch the tank water and the reason why.

IssuesFamily members could reach the tank, and the reason tap water must never be added had not been shared. The owner also had not recognized that in such a small tank even a little fresh water shifts the gravity greatly.

ImprovementAgree as a family that only the owner manages the tank, and post a notice: no tap water. Keep dechlorinated fresh water for top-offs in a dedicated container and teach the child to add it a little at a time together with you. Keep emergency seawater at the same temperature and specific gravity in stock.

Night in June. While cleaning the tank, you touched a Hypselodoris festiva bare-handed and then rubbed your eye with that hand. A few minutes later the eye stings badly, tears will not stop, and the eyelid is red. There is nudibranch mucus on your hand. You have running water and eye drops at home. Gloves are beside the tank but were not used.

Which is the most appropriate first action?

1. Wash your hands with soap, flush the eye under running water for at least 10 minutes, and see an eye doctor if the pain continues
2. Put in OTC eye drops and rub until the stinging subsides
3. Washing the eye with seawater will neutralize the nudibranch's toxin
4. The stinging is temporary, so close your eyes and go to sleep

AnswerA. Wash your hands with soap, flush the eye under running water for at least 10 minutes, and see an eye doctor if the pain continues

ExplanationHypselodoris festiva and similar species carry defensive chemicals from their sponge food in their mucus and on their body surface, which cause strong irritation and inflammation on contact with the mucous membranes of the eyes or mouth. First wash your hands with soap to remove the mucus, then flush the eye under running water for at least 10 minutes. If pain, redness or blurred vision persists, see an eye doctor and explain that you rubbed your eye with a hand that had touched a toxic marine mollusk. Eye drops do not remove the toxin, and rubbing damages the cornea. Washing the eye with seawater adds irritation and introduces bacteria. Going to sleep lets the inflammation progress unnoticed. The basic rule is to wear gloves for tank work and not touch your eyes or mouth afterward.

IssuesThe owner did not know that nudibranch defensive chemicals harm human mucous membranes and touched their face with a bare hand that had handled one. The habits of wearing gloves for tank work and washing hands afterward were not established.

ImprovementWear gloves for tank work and always wash hands with soap before touching your face. Post the procedure for eye contact: flush under running water for 10 minutes, then see an eye doctor. Check a field guide for potentially toxic species and strictly follow the no-touching rule.

Morning in May. On a walk along the shore, your small dog, let off the leash, picked up a sea hare from a tide pool and has purple fluid around its mouth. The sea hare is torn and the dog may have swallowed part of it. The dog is drooling and licking its lips repeatedly. The owner figures it is a sea creature so it is probably fine.

Which is the most appropriate first action?

1. The purple fluid is harmless, so rinse the mouth with seawater and continue the walk
2. Make the dog lick salt to induce vomiting
3. Remove what is left in the mouth, keep the remains, and call the vet for instructions
4. Watch, and go to the vet if the dog vomits

AnswerC. Remove what is left in the mouth, keep the remains, and call the vet for instructions

ExplanationSea hares can store toxic substances derived from the algae they eat, and a dog that eats one may vomit or show neurological signs. The purple fluid is a defensive secretion; the bigger concern is the body tissue that was swallowed. The response is to remove any remaining tissue from the mouth, keep the remains, and call the vet for instructions. Telling them how much was eaten and when helps the diagnosis. Making the dog lick salt to induce vomiting risks salt poisoning and must never be done. Assuming it is harmless and continuing the walk, or waiting for vomiting, risks being too late. On the shore, keep the dog on the leash and do not let it mouth tide-pool animals.

IssuesThe owner let the dog off the leash on the shore, creating a situation where it could mouth tide-pool animals. They did not know sea hares and nudibranchs are toxic and assumed sea creatures were harmless. Thinking of a dangerous folk remedy like salt to induce vomiting also showed a knowledge gap.

ImprovementKeep the leash short on the shore and beach and keep the dog away from tide pools. Set the ingestion procedure: clear the mouth, keep the remains and call, follow instructions. Carry contact numbers for your regular vet and an emergency (after-hours) animal hospital. Never induce vomiting on your own judgment.

Night in September. You planned to return a Hypselodoris festiva whose sponge food has run out to the collection site tomorrow morning, but a typhoon has closed the road to the coast and it will be at least three days before you can get there. The nudibranch's body is shrunken and its rhinophores barely come out. Water quality and gravity are normal, temperature 20°C. The owner feels helpless.

Which is the most appropriate response during this period?

1. Find another stretch of coast you can reach and release it in a different sea tonight
2. Keep it dark and quiet, maintain water quality, gravity and temperature, and return it to the collection site as soon as the road reopens
3. It might eat anything, so add vegetables or prepared food every day
4. A weakened nudibranch is only suffering, so euthanize it in the freezer

AnswerB. Keep it dark and quiet, maintain water quality, gravity and temperature, and return it to the collection site as soon as the road reopens

ExplanationReleasing it into a sea other than the collection site risks introducing a species or pathogens not found in that area and should be avoided for the sake of the ecosystem. The coast in a typhoon is also dangerous to human life. What you can do is reduce stress by keeping it dark and quiet, maintain water quality, gravity and temperature perfectly to limit energy loss, and return it to the collection site as soon as the road reopens. Nudibranchs can tolerate a few days without food, but they do not eat prepared food or vegetables, which only rot and foul the water. Euthanasia should be decided in consultation with a professional, and freezing is not a procedure to carry out on your own. Test ammonia and gravity daily until the return, and reconsider keeping after returning it.

IssuesThe plan to return it was made only after the food ran out, so it was too late for a typhoon, a foreseeable weather event. The idea of releasing it elsewhere showed a lack of understanding of the problem of introducing non-native species and pathogens.

ImprovementPlan the return when the food is down to half, check the forecast and act early. Make the release site always the collection site and never release into another sea. When an animal is weak, keep it dark, quiet and in good water to conserve its strength, and limit keeping to short-term observation.

Evening in October. Heavy rain has prompted an evacuation order for your area. Your 10 L tank holds two Hypselodoris festiva and a sponge-covered stone. Pets cannot be taken to the shelter, and a power outage is possible. The tank is glass and heavy; you have a sealable container that can hold seawater and a battery-powered air pump.

Which is the most appropriate response in this situation?

1. Load the whole tank into the car and manage it in the shelter parking lot
2. Put the animals and stone in a sealed container filled with seawater, place it somewhere dark and cool, run the battery-powered air pump, and evacuate
3. Release the nudibranchs in a nearby river and evacuate
4. Sneak them into the shelter in a container and keep them in the restroom

AnswerB. Put the animals and stone in a sealed container filled with seawater, place it somewhere dark and cool, run the battery-powered air pump, and evacuate

ExplanationHuman evacuation comes first; never take risks for the animals' sake. Nudibranchs are vulnerable to moving and shaking, a glass tank in a car risks breaking or tipping, and the shelter parking lot offers no temperature control. The realistic best option is to put the animals and their food stone in a sealed container filled with seawater, place it somewhere dark and cool indoors, provide oxygen with the battery-powered air pump, and evacuate. They can tolerate a few days without food in the dark. A river is fresh water and releasing them there kills them instantly. Sneaking them into the shelter violates the rules and strains relations with other evacuees. On returning home, check water quality and, if the animals are weak, decide to return them to the collection site. Deciding how to handle disasters before you start keeping is the premise.

IssuesThe disaster evacuation plan did not cover the nudibranchs, forcing a decision on the day. The idea of releasing marine animals in a river showed a lack of understanding that fresh water kills them instantly and of the impact on the ecosystem.

ImprovementMake a disaster plan before keeping, and store a sealable container, battery-powered air pump and artificial seawater with your emergency supplies. Assume pets cannot be taken to the shelter and write out the procedure for leaving them at home. Understand that these are short-lived animals that cannot be evacuated, and collect the minimum number.

Morning in November. The owner has been cleaning the nudibranch tank bare-handed for two months. Two small reddish-purple lumps have appeared on the back of the hand; after three weeks they have not healed and are slowly growing. Pain is mild and there is no fever. The owner assumes they are pimples and keeps applying OTC ointment.

Which is the most appropriate follow-up?

1. Switch to a different acne ointment and watch for another month
2. Lance the lumps with a needle and squeeze out the contents
3. Getting rid of the tank will cure it, so discard the nudibranchs
4. See a dermatologist and tell them you have been working in a marine tank bare-handed

AnswerD. See a dermatologist and tell them you have been working in a marine tank bare-handed

ExplanationWhen someone who works in a marine tank bare-handed develops reddish-purple lumps on the hand that will not heal and slowly grow, fish-tank granuloma from nontuberculous mycobacteria is suspected. The bacteria enter through small cuts, progress over weeks to months, and if neglected can spread to joints and tendons. The response is to see a dermatologist and be sure to mention the bare-handed marine tank work. Naming the likely organism leads to the right tests and treatment. Watching with ointment or lancing with a needle causes worsening and spread. Discarding the tank does not heal infected tissue; a medical visit is necessary. From now on, wear gloves for tank work and do not work on days you have a cut.

IssuesThe owner did tank work without gloves for a long time, unaware of the risk of skin infection from bacteria in seawater. A skin change that would not heal was self-diagnosed as pimples and the medical visit was put off.

ImprovementAlways wear gloves for tank work and wash with soap afterward. If a cut or skin change on the hand does not heal within three weeks, see a dermatologist and mention that you handle a marine tank. Ask a family member to do the work when your immunity is low.

Night in July. After removing a Hypselodoris festiva that died from body-surface melting, the owner only rinsed the 10 L container lightly with tap water and the next day is about to start keeping a new animal from a different shore in the same container with the same rock. The previous animal's mucus and broken-down tissue remain in the crevices of the rock.

Which is the most appropriate assessment of this plan and response?

1. No problem; replacing the seawater removes any effect of the previous animal
2. Wash the container and rock thoroughly in fresh water, dry them, and set up again with new seawater before use
3. Disinfect the container with bleach and fill it with seawater without rinsing
4. The previous animal's remains will feed the new one, so leave them

AnswerB. Wash the container and rock thoroughly in fresh water, dry them, and set up again with new seawater before use

ExplanationThe broken-down tissue and mucus of an animal that died from melting are loaded with decay bacteria, and putting a new animal in with them still in the rock crevices triggers water deterioration and body-surface breakdown again. The correct response is to wash the container and rock thoroughly in fresh water to remove all remains, dry them, then set up again with new seawater. Replacing the seawater alone leaves the remains. Bleach is powerful, but if rinsing is insufficient it is fatal to invertebrates; if used, rinse thoroughly with plenty of water and dry. Nudibranch remains are not food, only a source of decay. Treat any container where an animal melted as contaminated and manage its equipment separately.

IssuesThe owner thought a light rinse was enough for a container still holding a dead animal's tissue, not understanding the effect decay bacteria would have on the next animal. They had no basic hygiene procedure for cleaning and drying equipment.

ImprovementAfter a death or melting, wash containers and rock thoroughly in fresh water and dry before reuse. Avoid detergent and bleach, or if used, rinse with plenty of water and dry thoroughly. Keep isolation-container and main-tank equipment separate and never share pipettes or containers.

8 p.m. in June. Because the water was slightly cloudy, the owner replaced all the water in the 20 L tank with freshly mixed artificial seawater. Thirty minutes later, all three Hypselodoris festiva have fallen off the glass and lie contracted and motionless. The new seawater is at 1.026 and 23°C, 3°C colder than before. The old water has been thrown away.

Which is the most appropriate first life-saving measure here?

1. Mix another batch of seawater and do another full water change
2. Measure and log gravity and temperature, bring the temperature back gradually with a heater, aerate and dim the lights
3. Return each animal to the rock by hand and watch
4. Turn aeration and lighting to maximum to stimulate them

AnswerB. Measure and log gravity and temperature, bring the temperature back gradually with a heater, aerate and dim the lights

ExplanationThe full water change changed gravity and temperature at once, and all the animals are in osmotic and temperature shock. Nudibranchs cannot be given CPR; the life-saving measure is stabilizing the environment itself. First measure and log gravity and temperature, bring the water back to the original temperature gradually with a heater at 1–2°C per hour, provide oxygen with aeration and dim the lights. Another full water change on animals that have already suffered a change inflicts a second shock. Returning them to the rock by hand causes tears. Strong light and strong aeration add stress and physical injury. Do not touch them until morning; rhinophores coming out is a sign of recovery. Isolate any that start to melt.

IssuesUnder the mindset of replacing everything when it clouds, the owner ignored the cardinal rule of water changes: same temperature, same gravity. Throwing away the old water left no way back, and a minor cloudiness was met with the largest possible change.

ImprovementLimit water changes to 1/4–1/3 and always match temperature and gravity. Mix the change water the day before and bring it to tank temperature. First remove the cause of cloudiness (debris, rotting food); do a full change only in emergencies such as medication contamination.

11 p.m. in February. An outage stopped the air pump and filter, and three hours later the power is still out. The two Hypselodoris festiva in the 10 L container have gathered on the glass near the surface with their gills spread wide. The temperature is stable at 18°C. The owner has no battery-powered air pump, but has a pipette and a cup.

Which is the most appropriate way to provide oxygen?

1. Scoop water with the cup and pour it gently onto the surface now and then to disturb the surface and promote gas exchange
2. Replace all the tank water with new seawater to add oxygen
3. Take the nudibranchs out of the water and set them on moist tissue to expose them to air
4. Add a commercial oxygen supplement for fish at double the standard dose

AnswerA. Scoop water with the cup and pour it gently onto the surface now and then to disturb the surface and promote gas exchange

ExplanationNudibranchs gathering near the surface with gills spread is a response to falling dissolved oxygen. Without an air pump, you can add oxygen by scooping water with a cup and pouring it gently onto the surface, disturbing it to increase contact with air. Repeating this now and then gets you through several hours. Take care not to pour directly onto the animals. A full water change causes sudden gravity and temperature changes and does more harm than the oxygen shortage. Taking them out of the water is fatal through drying and tears. Overdosing supplements throws off the water chemistry and their safety for invertebrates is not guaranteed. After power returns, watch for suction when the pump restarts, and get a battery-powered air pump.

IssuesNo backup for providing oxygen in an outage was prepared, and there was no battery-powered air pump. Without knowing the oxygen-shortage behavior of nudibranchs (gathering at the surface), the owner would also have been slow to notice the problem.

ImprovementKeep a battery-powered air pump and spare batteries beside the tank. Write out the outage procedure: disturb the surface, check temperature, watch for suction on restart. Increase water volume and keep the number of nudibranchs to a minimum for an oxygen margin.

1 a.m. One Hypselodoris festiva's back has turned cloudy white and begun to melt, trailing strands of mucus. There are two others in the same 15 L tank. The owner is calling an emergency (after-hours) animal hospital and wondering whether to bring it in right away. Water quality is normal, gravity 1.024, temperature 20°C. An isolation container and spare seawater are available.

Which is the most appropriate action here?

1. Transport it to the emergency hospital right now and request treatment
2. Suck the melting animal up with a pipette and move it to another rock in the main tank
3. Isolate the melting animal in a container of spare seawater and change 1/3 of the main tank water to protect the other two
4. Move all the animals together to a new container and reset the main tank

AnswerC. Isolate the melting animal in a container of spare seawater and change 1/3 of the main tank water to protect the other two

ExplanationThere is effectively no treatment an emergency hospital can offer for body-surface breakdown in a nudibranch, and few clinics see invertebrates at all. The shaking and temperature changes of transport would also burden the remaining animals. The best you can do in the middle of the night is isolate the melting animal in a container of spare seawater to stop the broken-down tissue and mucus spreading, and change 1/3 of the main tank water at the same temperature and gravity to protect the other two. Sucking it up with a pipette tears it further, and leaving it in the main tank continues the contamination. Moving every animal and resetting the tank inflicts a sudden change and endangers the other two as well. At night, limit yourself to isolation and a water change; the next day, consult a clinic or aquarium familiar with invertebrates with photos and a history.

IssuesThe owner did not know the limits of what an animal hospital can do for a nudibranch and tried to rely on transport. No action plan for melting (isolate, change water, protect the others) had been decided in advance.

ImprovementSet the basic procedure for melting—isolate, change water, protect the others—and post it. Research in advance clinics or aquariums that can advise on invertebrates, and keep species photos and water-quality logs ready. Decide whether to keep them at all on the premise that they are short-lived with few treatment options.

Night in May. The edge of a Hypselodoris festiva freed from the pump is torn, oozing clear mucus and faintly tinted body fluid. The owner thinks it is bleeding and is about to press the wound with tissue to stop it, then take the animal out of the water to dry the wound. A container of spare seawater is on hand.

Which is the most appropriate treatment here?

1. Press the wound with tissue to stop the bleeding and return it to the tank once dry
2. Apply a styptic to the wound and then return it to seawater
3. Hold the wound closed with your fingers underwater for 10 minutes
4. Do nothing to stop bleeding; leave it to rest in a container of clean seawater with no flow, and observe until the next day without touching

AnswerD. Do nothing to stop bleeding; leave it to rest in a container of clean seawater with no flow, and observe until the next day without touching

ExplanationNudibranchs have no blood or clotting system like humans and mammals; what oozes from a tear is body fluid and mucus, not something to be stopped by pressure. Pressing with tissue tears the soft body further, and taking it out of the water is fatal through drying. Styptics and other medications are harmful to invertebrates, and pressing with fingers also widens the tear. The correct response is to attempt no bleeding control, leave it to rest in a container of clean seawater with no flow, and observe until the next day without touching. Small tears can be covered by mucus and recover; if melting begins, keep it isolated to protect the main tank. The basics of life-saving care come down to three things: do not touch, do not dry, maintain water quality and temperature.

IssuesThe owner applied mammalian bleeding-control logic to a nudibranch and was about to do the most harmful things possible: pressing and drying. They did not understand the nudibranch's body or that life-saving care means stabilizing the environment and not touching.

ImprovementSet the rule for nudibranch life-saving care—do not touch, do not dry, maintain water quality and temperature—and post it. Keep a flow-free container and spare seawater ready for resting torn animals. Fit sponge on the pump intake to eliminate the cause of tears in the first place.