Sturgeon case method: 50 questions

7 p.m. on a July evening. A 2-year-old sterlet (45 cm) in an indoor 120 cm tank is circling slowly along the wall with its snout out of the water, gulping. Its gills are opening and closing faster than usual. The thermometer reads 27°C and only one air pump is running. Until this morning it was foraging energetically on the bottom.

Which is the most appropriate first action?

1. Assume it wants food and give it extra pellets
2. Turn aeration to maximum and lower the water temperature with a frozen bottle at no more than 1°C per hour
3. Put a large amount of ice directly into the tank to bring it down to 20°C at once
4. Watch until tomorrow morning and see the vet if nothing changes

AnswerB. Turn aeration to maximum and lower the water temperature with a frozen bottle at no more than 1°C per hour

ExplanationGulping at the surface with the snout out is the classic sign of oxygen shortage in sturgeon. A high temperature of 27°C reduces dissolved oxygen while increasing the fish's oxygen demand, so first increase aeration to supply oxygen, then float a frozen plastic bottle to cool the water gradually at no more than 1°C per hour. Dumping in a lot of ice causes a sudden temperature difference that harms the fish and overcools spots locally. Feeding increases oxygen consumption through digestion and leftover food worsens water quality, making things worse. Left until morning, high temperature and oxygen shortage combine and the fish is likely to die overnight. If there is no improvement 1–2 hours after treatment, see the vet the same day.

IssuesSummer temperature control was inadequate, allowing 27°C, and with only one air pump there was no margin in oxygen supply. Knowing the signs of oxygen shortage, the owner might have noticed the rising temperature in the morning.

ImprovementInstall a tank chiller or cooling fan and keep the water below 25°C year-round. Use two air pumps and several air stones. In summer, record the temperature morning and evening and set a rule to start cooling once it exceeds 26°C.

Afternoon of an extremely hot August day. A 4-year-old bester (80 cm) in an outdoor round FRP tank (1,500 L) is swimming unsteadily with its body tilted and sometimes stops with its body resting on the bottom. The water is 28°C. A cooling fan is running but cannot keep up. The water is clear and was changed just last week.

Which is the most appropriate response in this situation?

1. Put up shade netting, turn aeration to maximum, cool gradually with ice packs or frozen bottles, and contact an animal hospital
2. The temperature is the cause, so pour in large amounts of tap water with a hose to drop it at once
3. The swimming is abnormal, so add the recommended dose of fish medication as a bath
4. Feed more than usual to build up its strength

AnswerA. Put up shade netting, turn aeration to maximum, cool gradually with ice packs or frozen bottles, and contact an animal hospital

ExplanationSturgeon are cold-water fish, and 28°C is a lethal temperature that can kill within hours. Tilting and resting on the bottom mean heat stress is advanced, so first block the sun with shade, turn aeration to maximum to secure oxygen, lower the temperature about 1°C per hour with ice packs or frozen bottles, and contact an animal hospital that treats fish. Pouring in tap water all at once damages the scaleless skin and gills with chlorine and a sudden temperature difference, and the fish can die of shock. This is not a disease, so fish medication is pointless, and a medicated bath at high temperature adds to the burden. Food increases oxygen consumption through digestion and worsens the condition.

IssuesThere was no cooling plan for extreme heat days for the outdoor tank, and the owner did not anticipate that a fan alone cannot cope on days with high air temperature. With no sun shade, direct sunlight drove the temperature up. Action was also delayed until 28°C was reached.

ImprovementFit the outdoor tank with shade netting and a roof, and install a tank chiller. Start cooling the day before extreme heat is forecast, and keep ice packs and frozen bottles on hand. Make 26°C the trigger for action and act before 28°C is reached.

Two weeks after bringing a juvenile sterlet (20 cm) into a newly set up 90 cm tank. It has been fed three times a day. This morning the gills look dark red and are opening and closing rapidly. Body mucus has increased, giving a cloudy white look, and it is often near the surface. The water is slightly cloudy, and water quality has never been tested.

Which is the most appropriate first action?

1. Cloudiness proves the filter is not working, so scrub the filter media thoroughly in tap water
2. Test ammonia and nitrite with strips, do a 1/3 water change, stop feeding, and see the vet the same day if there is no improvement
3. Treat it as early white spot disease and raise the water temperature to 30°C
4. Extra mucus is normal, so keep feeding the same amount and watch

AnswerB. Test ammonia and nitrite with strips, do a 1/3 water change, stop feeding, and see the vet the same day if there is no improvement

ExplanationPutting a heavy-feeding sturgeon into a just-started tank with no established filter bacteria and feeding three times a day sends ammonia and nitrite soaring. Dark red gills, rapid breathing and increased mucus are classic signs of ammonia/nitrite poisoning, and scaleless sturgeon are affected quickly. First confirm the readings with test strips, do a 1/3 water change with temperature-matched water to dilute the toxins, and stop feeding to reduce the source. If there is no improvement, see the vet the same day. Washing filter media in tap water kills even the few bacteria that have grown, making things worse. It is not white spot disease, and 30°C is fatal to a cold-water sturgeon. Increased mucus is a defensive response to irritation, not normal.

IssuesThe fish was added before filter bacteria had established, and heavy feeding on top of that let toxins accumulate. The owner had no test strips and overlooked the warning of cloudy water. The filtration was not designed for a sturgeon's large waste output.

ImprovementCycle a new tank for several weeks before adding fish. For the first month after introduction, test ammonia and nitrite daily and change water immediately if detected. Feed juveniles small amounts and remove leftovers the same day. Only rinse filter media lightly in tank water.

An October morning. You notice something white and cotton-like on the snout of a 3-year-old sterlet (50 cm) in an indoor tank. It is where a small wound formed last week from rubbing its nose on the wall of the rectangular tank. It is eating, but still keeps rubbing its snout on the wall. The water is 20°C and has not been changed for two weeks.

Which is the most appropriate first action?

1. Rub the cotton-like growth off with your finger to clean it
2. Add salt to the whole tank at a concentration you saw online for a salt bath
3. Do a 1/3 water change to improve water quality, take photos and see the vet within a few days
4. It is eating, so judge it fine and leave it

AnswerC. Do a 1/3 water change to improve water quality, take photos and see the vet within a few days

ExplanationWhite cotton-like growth on a wound is classic water mold (fungus), which often starts from wall-collision wounds. Water mold spreads with poor water quality and wounds, so first do a 1/3 water change with temperature-matched water, photograph the affected area, and consult an animal hospital that treats fish within a few days. Rubbing it off with a finger enlarges the wound and strips mucus from the scaleless skin, spreading infection. A salt bath at the wrong concentration is a heavy burden for sturgeon; with no scales, absorption is fast and dangerous, so never do it without a vet's instruction. Even if it is eating, left alone the snout erodes and it loses barbels and cannot find food. The root cause of snout rubbing in a rectangular tank must be fixed at the same time.

IssuesRepeated wall-collision wounds in a rectangular tank and a two-week gap in water changes that lowered water quality laid the groundwork for fungus. Nothing was done when the small wound first appeared, and early water mold was missed.

ImprovementPut pipes or boards in the tank corners to round them so the snout is not rubbed. Keep to weekly water changes, and keep the water especially clean when a wound is found. Check the snout and barbels every morning, and photograph any erosion or white deposits for the record.

A late-July night. A 5-year-old sterlet (55 cm) in an indoor 120 cm tank has several red hemorrhagic spots on its belly, and the skin between the scutes is red. The belly looks slightly swollen. It has been eating poorly for two days. The water is 26°C, and with a busy month only one water change was done. Leftover food has collected on the bottom.

Which is the most appropriate response?

1. Remove leftover food, do a 1/3 water change, lower the temperature, take photos and see the vet the same day
2. The red spots are injuries, so apply antiseptic directly with a cotton swab
3. Crush human antibiotics and mix them into the food
4. Darken the tank and wait a week for its appetite to return

AnswerA. Remove leftover food, do a 1/3 water change, lower the temperature, take photos and see the vet the same day

ExplanationHemorrhagic spots on the belly, redness between the scutes, a swollen belly and loss of appetite suggest Aeromonas infection, triggered by high temperature and poor water quality. As it progresses the fish dies of ascites or septicemia, so remove leftover food, do a 1/3 water change, lower the temperature gradually to improve the environment, and go to an animal hospital that treats fish the same day with photos. Antibiotics require a vet's diagnosis and prescription; giving human medicine on your own means the dose is wrong, and it is absorbed through the scaleless skin and can cause poisoning. Applying antiseptic directly strips mucus and makes things worse. Waiting a week is too late.

IssuesOne water change a month cannot cope with a heavy-feeding sturgeon's waste, and leftover food was left to spoil the water. The 26°C temperature also encouraged the outbreak. Checking the water when appetite dropped two days earlier would have caught it sooner.

ImprovementEven in busy periods, make the weekly water change a priority. Always remove leftover food 30 minutes after feeding. Loss of appetite is the first warning, so make it a habit to test temperature and water quality the same day. In summer, change water more often and keep it below 25°C.

A juvenile sterlet (25 cm) kept for three months in a 90 cm rectangular glass tank. Recently the tip of its snout has eroded white and the left barbels have become shorter. All day long the fish repeatedly pushes its head into a corner and then changes direction. Water quality is good and it eats, but it has started taking longer to find pellets on the bottom.

What is the cause of this situation and the most appropriate response?

1. It is not a disease but a normal change with growth, so do nothing
2. Damage from hitting the corners. Round off the corners with pipes or boards, and see the vet if the wound spreads
3. Malnutrition is the cause, so double the amount of food
4. Lower the water level by half to protect the snout

AnswerB. Damage from hitting the corners. Round off the corners with pipes or boards, and see the vet if the wound spreads

ExplanationSturgeon swim continuously along the walls and cannot back up, so in a rectangular tank they push their head into the corners and keep abrading the snout. A white, eroded snout and missing barbels are the classic result; the barbels are the sensory organs for finding food, so losing them slows foraging. The fix is to place pipes or curved boards in the corners so the fish can circle, or move it to a round tank, and see the vet if the wound spreads or white fungus grows. It is not a growth change; left alone the snout is destroyed and becomes a source of infection. More food does not heal the wound and worsens water quality. Lowering the water level leaves the corners in place and actually reduces oxygen.

IssuesThe owner lacked the basic knowledge that sturgeon are unsuited to rectangular tanks and did not recognize pushing into corners as abnormal. It went unnoticed until the barbels had shortened and foraging was affected.

ImprovementFrom the juvenile stage, keep it in a round tank or one with rounded corners. If using a rectangular tank, stand pipes or boards in all four corners to round them. Watch the snout and barbels daily and review the layout as soon as white erosion appears. Plan a large round tank in anticipation of it exceeding 1 m.

Yesterday, as a big cleanup, all the media in the external filter was washed thoroughly in tap water and the whole bottom was cleaned. This evening, the 3-year-old bester (70 cm) in the 150 cm tank is working its gills violently and drifting near the surface. A test strip shows high nitrite. The water is 21°C. The fish refuses all food.

Which is the most appropriate first action?

1. Assume the filter is broken and replace it with a new one
2. Add several times the recommended dose of a nitrite-reducing product for a quick effect
3. Do a 1/3 to 1/2 water change with temperature-matched, dechlorinated water, increase aeration, stop feeding and test daily
4. Nitrite falls on its own, so leave it alone and wait 2–3 days

AnswerC. Do a 1/3 to 1/2 water change with temperature-matched, dechlorinated water, increase aeration, stop feeding and test daily

ExplanationWashing filter media in tap water kills the filter bacteria with chlorine, and nitrite spikes. Nitrite blocks oxygen transport in the blood, so violent gill movement and drifting at the surface show the fish cannot take in oxygen. First do a larger water change with temperature-matched, dechlorinated water to lower the concentration, turn aeration to maximum to supply oxygen, and stop feeding to reduce the source of nitrite. Continue daily testing and water changes until the bacteria recover, and see the vet the same day if there is no improvement. Replacing the filter loses even more bacteria. Overdosing additives harms scaleless sturgeon. Waiting 2–3 days can mean death from nitrite poisoning.

IssuesNot understanding the role of filter bacteria, the owner washed the media in chlorinated tap water and wiped them out. Cleaning the bottom at the same time removed every refuge for bacteria. Heavy-feeding sturgeon generate toxins fast, so a filter crash is immediately life-threatening.

ImprovementOnly rinse filter media lightly in tank water, and do filter cleaning and bottom cleaning on different days. Use multiple filters and clean only one at a time. After any big cleanup, test nitrite from the next day. Keep dechlorinator and test strips on hand.

November. A 6-year-old bester (90 cm) in an indoor round tank (1,000 L) has not responded to sinking pellets for three days and only swims slowly near the bottom. No wounds or spots are visible on the body. The water is 18°C, and ammonia and nitrite are not detected. Last week a large new flow pump was added to the tank.

Which is the most appropriate response?

1. Judge the water too cold and raise it to 25°C with a heater
2. Give a large amount of frozen bloodworms to stimulate appetite
3. A fish can go a month without eating, so do nothing
4. Check whether the new pump's current is too strong and reduce it; if no improvement, see the vet with a video

AnswerD. Check whether the new pump's current is too strong and reduce it; if no improvement, see the vet with a video

ExplanationWhen temperature, water quality and the body surface are all normal, suspect exhaustion or stress from an environmental change. A current that is too strong places excessive load on a sturgeon that swims constantly and leaves it no margin to forage on the bottom. The large pump added last week coincides with the change, so first reduce the flow and watch the response. If there is no improvement, internal disease or parasites are possible, so take a video and see the vet within a few days. 18°C is ideal for sturgeon; heating to 25°C reduces oxygen and adds strain. Pouring food into a tank with a fish that is not eating worsens water quality. Even for a large fish, more than three days without eating is abnormal, and leaving it for a month is dangerous.

IssuesThe owner did not watch the fish's reaction when new equipment was introduced and did not consider that a strong current can be stressful. The timing of the appetite loss was not connected to the environmental change.

ImprovementNote the date whenever equipment is added or changed, and watch appetite and swimming closely for a week. Adjust the current so the fish can circle easily and still stop on the bottom to forage. Set a rule to see the vet if it does not forage for three days running.

May. A 4-year-old sterlet (50 cm) in an indoor 150 cm tank has many tiny bubbles visible on the fin edges and the surface of the eyes. The fish is unsteady and loses its balance near the surface. Since yesterday the submersible pump's intake had risen close to the surface and was drawing in air, spewing a constant stream of fine bubbles. The water is 19°C and water quality is normal.

Which is the most appropriate first action?

1. Stop the pump that is drawing in air or submerge its intake, agitate the surface to release excess gas, and see the vet
2. The bubbles are parasites, so add fish medication
3. Assume oxygen is short and add another air pump
4. Pop the bubbles with a needle to remove them

AnswerA. Stop the pump that is drawing in air or submerge its intake, agitate the surface to release excess gas, and see the vet

ExplanationBubbles on the fins and eyes with unsteadiness suggest gas bubble disease from gas supersaturation. When a pump sucks in air and forces fine bubbles into the water, dissolved gas becomes excessive and bubbles form in the fish's blood and tissues. First stop the offending pump or submerge its intake fully to stop air entrainment, and agitate the surface vigorously to release gas to the air. Then consult an animal hospital that treats fish the same day. It is not parasites, so medication is useless and a burden. Air-pump bubbles are coarse and do not normally cause supersaturation, but adding more without removing the cause misses the point. Popping with a needle damages the eye and tissue and invites infection.

IssuesThe pump intake had risen near the surface as the water level dropped, and the owner missed the abnormal noise and fine bubbles of air entrainment. Evaporation loss was not topped up, and checking equipment was not a habit.

ImprovementCheck the water level daily and top up evaporation with temperature-matched water. Fix pump intakes where they are always well submerged. Treat unusual bubbling or noise as a sign of equipment trouble and inspect immediately. Know that bubbles on the eyes or fins mean suspecting gas bubble disease.

A February night. Half the water in an indoor tank (16°C) holding a 2-year-old sterlet (40 cm) was changed in one go with nearly 30°C hot water from the water heater. Immediately afterward the fish started spinning, repeatedly hitting the walls, and working its gills rapidly. The thermometer has risen to 23°C.

Which is the most appropriate first action?

1. Add a heater to warm it further and stabilize it
2. Add cold tap water to rush it back to 16°C
3. Increase aeration, turn off the lights to reduce stress, and bring the temperature back to the original at about 1°C per hour while watching
4. Spinning is play behavior, so ignore it and go to bed

AnswerC. Increase aeration, turn off the lights to reduce stress, and bring the temperature back to the original at about 1°C per hour while watching

ExplanationA sudden 7°C rise in temperature causes temperature shock, bringing on neurological signs like spinning and hitting the walls, rapid gill movement and oxygen shortage. It is especially dangerous for cold-water sturgeon. First increase aeration to secure oxygen, turn off the lights to reduce collisions, and bring the temperature back to the original at about 1°C per hour with frozen bottles or similar while watching. If it does not recover, see the vet the same day. Adding cold tap water at once causes a second shock plus chlorine and can be fatal. Heating further worsens oxygen shortage. Spinning is not play but a serious sign, and going to bed risks death overnight from wall collisions or suffocation.

IssuesThe owner did not know the importance of matching temperature during water changes and did a large change with hot water at once. There was no step of checking the new water with a thermometer. Changing half the water is also enough to cause a sudden shift in water quality.

ImprovementAlways match water-change water to the tank with a thermometer, within 1–2°C. Limit each change to 1/3 and pour slowly. Use dechlorinator. Make it a habit to watch the fish swim for 30 minutes after every water change.

September. A 3-year-old bester (75 cm) in an outdoor round tank barely opens its left gill cover, breathing only with the right, and repeatedly rubs its body against the sand. The edge of the gill looks whitish and swollen. Water quality, ammonia and nitrite are normal; the water is 22°C. A month ago, plants collected from a nearby pond were added.

Which is the most appropriate response?

1. The plants are the cause, so just remove them and watch for a week
2. Rub the gill directly with a cotton swab to clean off the dirt
3. Remove the plants, take video and photos, and see the vet within a few days for a gill examination
4. Add the recommended dose of a koi antiparasitic and treat it at home

AnswerC. Remove the plants, take video and photos, and see the vet within a few days for a gill examination

ExplanationHolding one gill shut, rubbing the body, and a swollen gill are classic behaviors of gill parasites. Plants collected from a wild pond easily bring in parasites and eggs, and the timing matches. The type of parasite can only be identified by examining the gills and skin under a microscope, so remove the plants that brought it in, take video and photos, and have it examined at an animal hospital that treats fish within a few days. Removing the plants alone does not reduce parasites already attached. Rubbing the gill with a swab damages the delicate gill and causes bleeding and infection. Some koi antiparasitics are highly toxic to scaleless sturgeon, and self-prescribed dosing leads to fatal accidents.

IssuesPlants from the wild were added without disinfection or quarantine, bringing in parasites. Adding plants at all was a problem, as sturgeon do not need them and can get trapped. The owner did not know what one-sided gill breathing meant, so observation was delayed.

ImprovementNever bring wild plants, water or animals into the tank. Keep the sturgeon tank free of plants and decorations, with a bare tank as the standard. Learn that uneven gill movement and body rubbing are signs of parasites, and get an examination early when seen.

A 2-year-old bester (60 cm) kept with five koi in an outdoor pond-style tank (3,000 L). Recently the scutes on its back stand out, its head looks large and its body has become thin. At feeding time the koi eat almost all the sinking pellets before they reach the bottom. The gills and body are normal and it swims normally. The water is 20°C.

Which is the most appropriate response in this situation?

1. Consider it a growth-phase body shape and continue the same feeding
2. Switch to floating food so it can eat before the koi do
3. Move the sturgeon to a separate tank or keep the koi away so sinking food reaches the bottom, and confirm it regains weight
4. Thinness is a disease, so give fish medication

AnswerC. Move the sturgeon to a separate tank or keep the koi away so sinking food reaches the bottom, and confirm it regains weight

ExplanationProminent scutes on the back with a large-looking head is the classic sign of a thin sturgeon. A sturgeon that forages on the bottom with its barbels rather than sight loses out to fast-feeding koi and becomes chronically underfed. The fundamental fix is a separate tank; if that is difficult, lure the koi elsewhere before feeding and get the sinking food to the bottom, for example by dropping it directly through a pipe, and confirm the body shape recovers in 1–2 weeks. If it does not recover, parasites or internal disease are possible, so see the vet. Floating food cannot be eaten with the sturgeon's downward-facing mouth. Thinness is not a disease but underfeeding, so medication is pointless.

IssuesFish with completely different feeding styles were kept together, and it took too long to notice the sturgeon was not getting food. No one watched who was eating at feeding time. Weight loss had progressed until the scutes stood out.

ImprovementKeep sturgeon alone or only with their own kind. If continuing the mix, feed the koi elsewhere at feeding time and drop sturgeon sinking food to the bottom through a pipe. Once a month, photograph the prominence of the back scutes and body width to catch thinness early.

7 a.m. A 2-year-old sterlet (45 cm) in an indoor 120 cm tank has pushed its head into the gap between the heater cover and the tank wall and is thrashing its body violently but cannot get out. The gills are moving but breathing is rapid. The heater was installed without a guard, 3 cm from the wall.

Which is the most appropriate first action?

1. Grab the tail and pull it backward with all your strength
2. Switch off the heater, remove it to widen the gap, and let the fish free itself by moving forward
3. The fish will manage on its own, so leave it and go to work
4. Drain all the water and rescue the fish dry

AnswerB. Switch off the heater, remove it to widen the gap, and let the fish free itself by moving forward

ExplanationSturgeon cannot swim backward, so once the head enters a gap they cannot back out on their own, and when swimming stops no water passes over the gills and they suffocate. The correct rescue is to switch off and remove the object trapping it (the heater), widen the gap, and let the fish free itself by moving forward. Pulling by the tail damages the skin between the scutes and the gills, and the head catching on equipment can cause fractures and bleeding. Left alone, it stays unable to swim and dies within hours. Draining the water takes the fish out of water so it cannot breathe, and the scaleless skin dries out with fatal damage. After rescue, direct current at the gills, confirm it starts swimming, and see the vet if there are wounds.

IssuesNot knowing that sturgeon cannot back up, the owner left a gap between the heater and the wall wide enough for the head to enter. No heater guard was used either, adding a burn risk. Equipment placement was never checked from the fish's point of view.

ImprovementFix all equipment flush against the wall with zero gaps. Enclose the heater in a guard, or better, move it to the filter side. After installation, look down into the tank every time to check for gaps wide enough for the fish's head. Morning and evening checks catch trapping early.

2 a.m. You are woken by a flapping sound. A 3-year-old sterlet (50 cm) has fallen onto the floor beside the 150 cm tank in the living room and is flopping. Part of the lid was open. Its body is starting to dry and has dust and hair stuck to it. The gills are moving, but part of a scute on the belly is chipped and oozing a little blood.

Which is the most appropriate first action?

1. Wipe the body with a dry towel before returning it to the tank
2. Lift it with wet hands, return it to the tank, support it horizontally in front of the current and watch until it swims off
3. It is injured, so pour antiseptic on it before returning it to the tank
4. Keep it in a basin of water until morning and return it to the tank once it is light

AnswerB. Lift it with wet hands, return it to the tank, support it horizontally in front of the current and watch until it swims off

ExplanationOut of water the gills stop working and the fish suffocates, and a scaleless sturgeon also suffers fatal damage from drying skin, so return it to the tank as fast as possible. Lift it with wet hands, support it horizontally in the tank facing the current so water passes over the gills, and watch until it swims on its own. A dry towel strips mucus and damages the skin. Antiseptic damages mucus and skin, and causes breathing trouble if it gets into the gills. A basin has too little oxygen and no room to swim, so it suffocates and will not survive the night. For the chipped scute and bleeding, keep the water clean, check the next day for fungus or swelling, and see the vet if bleeding continues or the wound is deep.

IssuesPart of the lid was open, and measures against jumping by a sturgeon that leaps when startled were inadequate. Environmental factors such as noise or vibration at night may have startled it. The water level may have been high with too little margin to the rim.

ImprovementUse a heavy or fixed lid covering the whole tank, and seal gaps around cables. Keep the water level at least 10 cm below the rim. Avoid sudden lighting or vibration around the tank at night. Keep gloves usable with wet hands and a bucket beside the tank for a quick response if it jumps.

During a tank move, a 4-year-old sterlet (50 cm) was scooped twice with a small dip net. The next day, the mucus on the side of its body where the net touched is cloudy white and the skin around the scutes is red. The fish is swimming but rubs that area against the wall. The new tank's water quality is good and the water is 20°C.

Which is the most appropriate response?

1. Wipe off the white area with a soft cloth
2. Stop feeding until it heals and leave the tank completely dark for a week
3. Keep the water clean, observe daily, and see the vet within a few days if the redness spreads or cotton-like fungus grows
4. Mix several over-the-counter fish medications and add them to the tank

AnswerC. Keep the water clean, observe daily, and see the vet within a few days if the redness spreads or cotton-like fungus grows

ExplanationWhen a scaleless sturgeon is rubbed by a net, the skin's mucus is stripped and shows as cloudiness and redness. Even if the abrasion itself is minor, skin that has lost its mucus protection is prone to invasion by water mold and bacteria. The response is to keep the water clean, remove leftover food, observe daily, and see the vet within a few days if the redness spreads, cotton-like fungus grows, or it swells. Wiping with a cloth strips more mucus and enlarges the wound. Stopping food and leaving it for a week weakens the fish and slows healing. Mixing several medications raises toxicity through interactions and is extremely dangerous for a scaleless sturgeon that absorbs quickly.

IssuesUnaware of the danger of using a net on a scaleless fish, the owner scooped it twice with a small net the wrong size for its body. Preparation for the move was poor, with no thought given to moving it in a container or bag.

ImprovementMove sturgeon in a large bag or container, scooping them with the water. If a net is unavoidable, use a soft, fine-mesh net larger than the fish and do it in one go. Check the body surface daily for three days after a move and keep a photo record of any wounds.

A 3-year-old bester (70 cm) brought home by car in an hour-long drive from the shop. It was in a bag with corners, so it thrashed inside, and on arrival two scutes on its back are chipped and oozing blood, and the snout is scraped and red. Released into the tank, it swims slightly tilted. The bag water is 20°C, the tank 19°C.

Which is the most appropriate first action?

1. Float the bag for 30 minutes or more to match temperature, release it, confirm it is stable in front of the current, photograph the wounds, and see the vet if bleeding continues
2. It is bleeding, so apply a human styptic to the wounds before releasing it
3. It is bleeding, so put it in strong salt water immediately to disinfect
4. The tilt is just unfamiliarity, so tear the bag open, release it immediately and leave it until tomorrow

AnswerA. Float the bag for 30 minutes or more to match temperature, release it, confirm it is stable in front of the current, photograph the wounds, and see the vet if bleeding continues

ExplanationA fish agitated by transport uses a lot of oxygen and is easily injured. First float the bag in the tank to match the temperature, and after release watch whether its body stabilizes level in front of the current. Chipped scutes and abrasions cannot be treated underwater, so keep the water clean, record them in photos, and see the vet if bleeding does not stop, the tilt persists, or swelling or fungus appears the next day. Human styptics damage mucus and skin and are dangerous if they enter the gills. Strong salt water is a severe stress for scaleless sturgeon, which are easily affected by osmotic changes. Tilted swimming can also result from impact or oxygen shortage, and leaving it unobserved risks deterioration overnight.

IssuesA large sturgeon was put in a bag with corners, creating conditions for it to thrash and chip its scutes during transport. Oxygen and water volume were inadequate for the trip length, and there was no plan for observation and treatment on arrival.

ImprovementFor transport, tie a thick bag into a round shape or use a large cooler box, fill with oxygen, and keep it dark and cool. On arrival, match temperature for 30 minutes or more and watch swimming for an hour. Photograph any chipped scutes and check the wounds again the next day.

A 1-year-old sterlet (30 cm) kept in an indoor 90 cm rectangular tank. Rubbing against the walls has cost it two barbels on each side, and when sinking pellets are dropped it passes right over them dragging its snout along the bottom, never reaching the food. In a week it has become visibly thin and the belly is sunken. Water quality and temperature are normal.

Which is the most appropriate response?

1. It can find food by sight even without barbels, so increase the amount and wait
2. Bring food to its mouth with tweezers or by hand, move it to a tank with rounded corners, and see the vet about the wounds and nutrition
3. It is not eating, so switch to floating flake food
4. Thinness is a sign of disease, so add fish medication

AnswerB. Bring food to its mouth with tweezers or by hand, move it to a tank with rounded corners, and see the vet about the wounds and nutrition

ExplanationSturgeon have poor eyesight and find food with the barbels and sensory organs on the snout. Without barbels they cannot find food even when it is right beside them, and head toward starvation. As first aid, bring food to the mouth with tweezers or by hand to make sure it eats and keeps its strength. At the same time, fix the cause by rounding the corners of the rectangular tank or moving it to a round tank, and consult an animal hospital that treats fish about the snout wounds and nutritional state. Barbels can regenerate over time, but assisted feeding in the meantime makes the difference between life and death. More food it cannot find only worsens water quality. Floating food cannot be eaten with a downward-facing mouth. Thinness is underfeeding, so medication is pointless.

IssuesNot knowing that the snout and barbels get abraded in a rectangular tank, the owner did not improve the environment until all four barbels were lost. It went unnoticed for a week that dropped food was not being eaten, causing weight loss.

ImprovementUse a round tank or one with rounded corners from the juvenile stage. Watch feeding until the fish has actually finished eating and confirm intake by whether food is left. Check the barbels and snout daily and review the setup as soon as loss begins. Get it used to hand-feeding.

Plants attached to driftwood were added to a 120 cm tank to improve its looks. In the morning, a 2-year-old sterlet (40 cm) has wedged its body between the driftwood and the plant roots; from thrashing, its tail fin is torn and the tip is in tatters, and blood oozes from between the scutes. The gills are still moving but breathing is rapid, and the fish is tired and sluggish.

Which is the most appropriate first action?

1. Lift out the whole driftwood with the fish, and free it on a dry surface
2. Thrashing worsens the wounds, so do nothing until it frees itself
3. Move the driftwood and plants underwater to open the way in front of the fish, let it free itself, then remove the driftwood and plants
4. The tail fin is torn, so trim it neatly with scissors

AnswerC. Move the driftwood and plants underwater to open the way in front of the fish, let it free itself, then remove the driftwood and plants

ExplanationSturgeon cannot back up; once the head enters driftwood or plant roots they cannot get out and thrashing enlarges the wounds. Rescue by moving the obstacle underwater to open the way ahead so the fish can move forward and free itself. If it is too exhausted to swim, support it horizontally in front of the current so water passes over the gills. Remove the driftwood and plants that caused it and return to a bare tank. Taking it out of the water is fatal through suffocation and drying. Left alone, it cannot swim and suffocates within hours. Cutting the tail fin with scissors adds wounds and invites infection. For the torn fin and bleeding, keep the water clean and monitor, and see the vet within a few days if swelling or fungus appears.

IssuesNot understanding the danger of decorations in a sturgeon tank, the owner put looks first and added driftwood and plants. They did not know its habit of entering gaps head-first and being unable to get out. It was not noticed until morning, and the fish was trapped until exhausted.

ImprovementKeep driftwood, plants and hiding places out of the sturgeon tank; a bare tank is the standard. When changing the layout, check for gaps the fish's head can enter. Make checks before bed and after waking a habit so trapping is found early.

11 p.m. When the tank light was switched on suddenly in a pitch-dark room, a 3-year-old sterlet (50 cm) was startled, swam at full speed and crashed into the glass wall. Its snout is split red and bleeding; it lay motionless on the bottom for a while but is now swimming slowly. It seems bothered by the snout and rubs it on the wall a little.

Which is the most appropriate first action?

1. Turn off the lights to reduce stress, increase aeration, watch its swimming and gill movement, and keep the water clean
2. Apply ointment to the bleeding area with a cotton swab
3. It is bleeding, so immediately replace all the water
4. The collision was a one-off, so leave the lights on and go to bed

AnswerA. Turn off the lights to reduce stress, increase aeration, watch its swimming and gill movement, and keep the water clean

ExplanationSudden lighting after darkness startles a sturgeon into a full-speed dash and a wall collision, a classic accident. First turn off the lights to reduce stress, increase aeration to secure oxygen, and watch whether gill movement and swimming are stable. Snout bleeding cannot be stopped underwater, so keep the water clean to prevent infection, and see the vet if swelling, fungus or spreading erosion appears from the next day. Ointment washes off underwater and damages mucus. A full water change causes a sudden shift in water quality and a secondary shock. With the lights left on, agitation continues and another collision is likely.

IssuesNot knowing that sturgeon bolt when startled by sudden light or vibration, the owner switched on the tank light abruptly in a dark room. A rectangular glass tank, where the head hits the wall on impact, also raised the risk.

ImprovementTurn on the room light first, then the tank light, and use a timer for gradual lighting. Avoid sudden movements and loud noises in front of the tank at night. Round off the tank corners to reduce collision damage. Check the snout wound again the next day.

Afternoon. A 1-year-old bester (35 cm) in a 1,000 L round tank has its belly sucked onto the intake of a powerful pump with no strainer, and cannot get free however it twists. The gills are moving but breathing is rapid. The skin around the intake is red and one scute has peeled up.

Which is the most appropriate first action?

1. Grab the fish with both hands and tear it off the intake
2. Switch off the pump to stop the suction, wait for the fish to free itself, and check its swimming in front of the current
3. Show it food on the far side of the intake to lure it off
4. The suction is temporary, so wait 30 minutes and see

AnswerB. Switch off the pump to stop the suction, wait for the fish to free itself, and check its swimming in front of the current

ExplanationA powerful pump intake with no strainer sucks a small bottom-dwelling sturgeon on and does not let go. First switch off the pump to stop the suction and wait for the fish to free itself. Once free, support it horizontally in front of the current, let water pass over the gills, and check that its swimming stabilizes. Tearing it off forcibly tears the skin and scutes further and damages internal organs. Lured by food, it still cannot overcome the suction. Waiting 30 minutes lets skin damage spread, and oxygen shortage progresses because it cannot swim. For the redness and peeled scute, keep the water clean and see the vet within a few days if swelling or fungus appears. Fit a strainer to the pump and cover the intake with a guard.

IssuesThe pump intake had neither strainer nor guard, exposing a small juvenile to powerful suction. Equipment safety was never checked against the fish's size.

ImprovementFit strainers and sponge guards to all intakes so a juvenile cannot be sucked on. Set pump flow to match the fish's strength and review it as it grows. After installing equipment, watch the fish for several hours to confirm it does not get stuck.

An uncovered submersible pump was placed on the bottom of a 150 cm tank to create current. In the morning, the lower half of the tail fin of a 4-year-old sterlet (55 cm) is cleanly cut off and blood is coming from the base of the fin. A fragment of scute was caught in the pump outlet. The fish cannot swim straight and drifts, tilted slightly.

Which is the most appropriate first action?

1. Stop the pump and fit a guard or remove it, increase aeration, watch the bleeding and swimming, and see the vet the same day
2. Tail fins regenerate, so do nothing and feed as usual
3. Dust flour on the wound to stop the bleeding
4. Increase the pump's flow to make it practice swimming

AnswerA. Stop the pump and fit a guard or remove it, increase aeration, watch the bleeding and swimming, and see the vet the same day

ExplanationWhen a fin is drawn into the intake or impeller of an uncovered submersible pump, it is severed and bleeds heavily. First stop the pump that caused the accident and fit a guard or remove it, and secure oxygen with aeration. Bleeding from the fin base is near major blood vessels and cannot be stopped underwater, so watch whether bleeding continues and whether it swims tilted, and consult an animal hospital that treats fish the same day. Fins can regenerate, but infection or blood loss can be life-threatening, so do not leave it. Dusting flour on the wound damages mucus, fouls the water and invites infection. Strong current on a tilted fish exhausts it until it sinks, risking suffocation.

IssuesAn uncovered submersible pump was placed directly on the bottom, in a position where a bottom-dwelling sturgeon's fins could be drawn in. The equipment hazard was not linked to the fish's behavior. It went unnoticed until a scute was caught.

ImprovementAlways use submersible pumps with guards and fit a sponge over the intake. Mount them flush against the wall, out of reach of a bottom-dwelling fish. Check the fins and scutes every morning, and inspect the equipment immediately if any cut or chip is seen.

Midday on a day off. A 6-year-old child grabbed the 2-year-old sterlet (40 cm) from the tank with dry hands and lifted it; it slipped, hit the rim of the tank and fell to the floor. The fish flopped on the floor and has abrasions on its belly and a split snout. The child's hand is also cut and bleeding from the scutes. The fish's gills are moving.

Which is the most appropriate first action?

1. Treat the child first and return the fish to the tank later
2. Return the fish to the tank with wet hands, support it in front of the current, confirm it swims, then rinse the child's cut under running water
3. Disinfect both the fish's and the child's wounds with the same antiseptic
4. Put the fish in a basin and leave it for several hours to calm down

AnswerB. Return the fish to the tank with wet hands, support it in front of the current, confirm it swims, then rinse the child's cut under running water

ExplanationOut of water, a sturgeon is in danger within minutes from suffocation and skin drying, so first return the fish to the tank with wet hands, support it horizontally in front of the current, and confirm the gills are moving and it swims on its own. A cut on the child's hand is not life-threatening and a few minutes' delay is fine, so after the fish is back, rinse it well under running water, disinfect, and see a doctor if swelling or redness develops. Antiseptic on the fish damages mucus and skin, and causes breathing trouble if it enters the gills. A basin has too little oxygen, and a sturgeon that cannot swim suffocates. For the split snout and belly abrasions, keep the water clean and see the vet if fungus or swelling appears from the next day.

IssuesThe child was in an environment where it could reach into the tank and had not been taught the danger of lifting with dry hands. The tank was left unattended with the lid open. The owner also did not realize that the sharp scutes can injure people.

ImprovementFit a fixed lid the child cannot open, and set a rule that the fish is only touched with wet hands and together with an adult. Keep thick gloves on hand, as sturgeon scutes cut hands. Share emergency procedures with the whole family.

10 p.m. on an August night; lightning has caused a power outage. An indoor 1,000 L round tank holds a 5-year-old bester (90 cm), and both the air pump and chiller have stopped. The water is 25°C and beginning to rise. There is no word on when power will return. On hand are one battery-powered air pump, a few ice packs and a flashlight.

Which is the most appropriate first action?

1. Start the battery-powered air pump immediately, hold the temperature down with ice packs, and check the fish's gills and swimming regularly with the flashlight
2. Nothing can be done until power returns, so sleep until morning
3. Keep stirring the water with a bucket for oxygen, and put all the ice packs in at once
4. Add a large amount of tap water to lower the temperature

AnswerA. Start the battery-powered air pump immediately, hold the temperature down with ice packs, and check the fish's gills and swimming regularly with the flashlight

ExplanationA large sturgeon has a very high oxygen demand and falls into oxygen shortage within hours once aeration stops. In an outage, first run the battery-powered air pump to maintain oxygen supply, float ice packs a little at a time to hold the temperature down, and check gill movement and surface gulping regularly with the flashlight. If you sleep, you will not notice the oxygen shortage progressing and may find the fish dead by morning. Stirring by hand has only a brief effect, and adding all the ice packs at once causes localized sudden cooling. A large addition of tap water harms the fish with chlorine and a sudden change in water quality. After power returns, confirm the pump and chiller have restarted.

IssuesThe risk of aeration and cooling stopping together in a summer outage had been considered, but there was only one battery pump and not enough spare batteries or ice packs. Preparation did not match a large fish's oxygen consumption.

ImprovementKeep at least two battery-powered air pumps and spare batteries, and install a type that starts automatically in an outage. In summer, keep several ice packs and frozen bottles in the freezer. Prepare a portable power station and confirm it has the capacity to run the chiller or fan.

Evening as a typhoon approaches. Heavy rain has raised the water in an outdoor round FRP tank (2,000 L) nearly to the rim, and heavier rain is forecast. Inside is a 4-year-old bester (85 cm). Near the tank is a drainage ditch that leads to a river. There is an overflow outlet, but it is almost blocked with fallen leaves.

Which is the most appropriate response?

1. Put the fish's life first and release it into the nearby river
2. Clear the leaves from the overflow outlet and cover the whole tank with a secured net to prevent escape
3. Leave the tank uncovered and let the rain change the water naturally
4. Pull the plug, drain all the water, and keep the fish in a bucket overnight

AnswerB. Clear the leaves from the overflow outlet and cover the whole tank with a secured net to prevent escape

ExplanationIf the tank overflows in heavy rain, the fish can be washed out with the water and reach the river via the ditch. Sturgeon are non-native in Japanese rivers, and because of the ecological impact, release is prohibited under local fisheries regulations and ordinances. The response is to clear the leaves blocking the overflow outlet to ensure drainage, and cover the whole tank with a firmly secured net to physically prevent escape. Release is illegal, and the fish itself would not survive the sudden change of environment. Without a cover, a jumping fish can be washed out. Draining the water and using a bucket leaves a large sturgeon unable to swim, and it dies of oxygen shortage.

IssuesThe outdoor tank's drain was not kept clean, and no advance measures were taken despite a heavy rain forecast. With the ditch and river so close, there was little awareness that an escape would directly become an invasive species problem.

ImprovementClean the overflow and drain outlets weekly and fit mesh to keep leaves out. The day before a typhoon or heavy rain forecast, lower the water level and secure the net. Share with the family that release is prohibited both legally and ethically, and research in advance who could take the fish if you can no longer keep it.

Returning from a three-night trip in August, you find the chiller on the indoor 150 cm tank has stopped and the water is 29°C. The 3-year-old sterlet (50 cm) is lying on its side on the bottom, with the gills moving only slightly. The water is cloudy and leftover food is rotting. The automatic feeder kept running.

Which is the most appropriate first action?

1. It is on its side, so judge it beyond saving and do nothing
2. Turn aeration to maximum, do a 1/3 water change with water of similar temperature while removing leftover food, cool gradually with ice packs, support the fish horizontally and prepare to see the vet immediately
3. Pour in cold tap water at once to bring it back to 20°C
4. A medicated bath is what it needs, so add several fish medications

AnswerB. Turn aeration to maximum, do a 1/3 water change with water of similar temperature while removing leftover food, cool gradually with ice packs, support the fish horizontally and prepare to see the vet immediately

ExplanationHigh temperature of 29°C combined with water fouled by rotting food has left the fish rolled over and in critical condition. If the gills are moving there is a chance of recovery, so first turn aeration to maximum to supply oxygen, remove leftover food while doing a 1/3 water change with water of similar temperature to dilute toxins, and cool about 1°C per hour with ice packs. Support the rolled-over fish horizontally so current passes over the gills, and at the same time contact an animal hospital that treats fish and prepare to go immediately. Pouring in cold tap water at once finishes it off with temperature shock and chlorine. Medication is not the cause and is highly toxic to a weakened fish. Giving up and doing nothing loses a life that could be saved.

IssuesNo thought was given to chiller failure during a long absence, and there was no remote temperature monitoring or backup cooling. The automatic feeder kept dropping food for a fish that could not eat, fouling the water. No one had been arranged to check on the tank.

ImprovementWhen away, use a thermometer with remote monitoring or alerts. Use two cooling systems, main and backup, with a fan as well. Set the automatic feeder to a small amount, and ask a friend or service to check when absent for more than two days. Post emergency contacts beside the tank.

9 p.m. A crack has appeared in a bottom corner of the 150 cm glass tank in the living room; water is seeping out and the level is starting to drop. Inside is a 4-year-old sterlet (55 cm). In the house are a storage box (120 L), a bucket and a battery-powered air pump. The water is 20°C. The fish is still swimming normally.

Which is the most appropriate first action?

1. The leak is small, so apply waterproof tape and watch until morning
2. Move the fish to the bucket, drain the tank completely and repair it
3. Take the fish out of the water, wrap it in a wet towel and go buy a new tank
4. Transfer tank water into the storage box, add the air pump, scoop the fish over in a bag, and check temperature and swimming

AnswerD. Transfer tank water into the storage box, add the air pump, scoop the fish over in a bag, and check temperature and swimming

ExplanationA cracked tank can shatter at any moment, and if the level drops a large sturgeon cannot swim and suffocates. First transfer the tank water to the largest container available, such as the storage box, supply oxygen with the battery-powered air pump, and move the fish over in a bag or container. Using the tank water avoids sudden changes in water quality and temperature. After the move, check swimming and gill movement, and arrange a replacement tank by the next day. Waterproof tape cannot withstand the water pressure, and if the glass gives way overnight the fish ends up on the floor. A bucket is too cramped to swim in and leads to oxygen shortage. Taking it out of the water in a wet towel, even briefly, stops the gills working and damages the scaleless skin.

IssuesAging of the glass tank holding a large fish and the load on its bottom corners had not been inspected. No large emergency container had been prepared, and a 120 L storage box is the bare minimum for a 55 cm fish.

ImprovementKeep an emergency container at least twice the fish's length (a large tub or pool) and a battery-powered air pump on hand. Inspect the tank monthly for cracks and silicone deterioration. Choose FRP or polyethylene tanks for large fish, and replace glass tanks early.

Putting a hand into the 1,000 L round tank for a water change, you feel a tingling in your fingertips. The 5-year-old bester (90 cm) inside is hanging still by the wall, swimming sluggishly and twitching its body now and then. The tank has three electrical devices: a heater, a submersible pump and a flow pump.

Which is the most appropriate first action?

1. You are worried about the fish, so put both hands in at once to rescue it
2. To find which device is at fault, touch each one underwater in turn
3. Withdraw your hand, switch off the breaker or unplug everything, and once the power is off inspect the devices and watch the fish's gills and swimming
4. Put on rubber gloves and carry on with the water change

AnswerC. Withdraw your hand, switch off the breaker or unplug everything, and once the power is off inspect the devices and watch the fish's gills and swimming

ExplanationA tingling in the water means an electrical device is leaking current, which is life-threatening for both people and fish. First withdraw your hand and switch off every outlet or breaker connected to the tank; only once the power is completely off, inspect each device to identify the leaking one and stop using it. The fish has been receiving continuous electrical stimulation, so after cutting the power watch whether gill movement and swimming recover, and see the vet the same day if it keeps rolling over or breathing irregularly. Putting both hands in risks electrocution, and feeling around devices underwater is even more dangerous. Rubber gloves are not full insulation, and the current to the fish continues.

IssuesSeveral electrical devices were in use without a ground-fault circuit interrupter or grounded outlet. Equipment was never inspected for deterioration, and the fish's sluggishness was not linked to leaking current.

ImprovementRun the tank's power through a power strip with a ground-fault circuit interrupter and ground it. Inspect cords and heaters for cracks monthly and replace old equipment. Make it a habit to switch off equipment before putting a hand in, and remember that abnormal twitching in the fish is a sign of leaking current.

Sunday morning. Half the water in the 150 cm tank was replaced with tap water, forgetting to add dechlorinator. Ten minutes later, the 3-year-old sterlet (50 cm) is working its gills violently, swimming in distress with its snout out at the surface, and its body mucus is turning cloudy white. The water was 20°C both before and after the change.

Which is the most appropriate first action?

1. Chlorine dissipates with time, so do nothing and wait
2. Change all the water with more tap water to dilute it
3. Take the fish out and move it to a bucket of tap water
4. Add the recommended dose of dechlorinator directly to the tank immediately, turn aeration to maximum, and watch the gills and swimming

AnswerD. Add the recommended dose of dechlorinator directly to the tank immediately, turn aeration to maximum, and watch the gills and swimming

ExplanationChlorine in tap water directly damages gill tissue, and in a scaleless sturgeon the body mucus is harmed too. Violent gill movement and distress at the surface are signs of chlorine gill damage. The fastest remedy is to add the recommended dose of dechlorinator directly to the tank to neutralize the chlorine and turn aeration to maximum to supply oxygen. Then watch whether gill movement settles, and see the vet the same day if it does not improve. Waiting for chlorine to dissipate lets gill damage progress. More tap water adds more chlorine. Moving it to a bucket of tap water keeps it bathed in chlorine, and it is too cramped to swim in, so it suffocates.

IssuesThe water-change routine was not firmly established and the dechlorinator was forgotten. Changing half the water magnified the effect of the mistake. The habit of checking the fish right after a water change was a good thing.

ImprovementFix the routine so water is dechlorinated and temperature-matched in the bucket before pouring, and post a checklist beside the tank. Limit each change to 1/3. Keep dechlorinator near the tank so it can be added at once if a mistake is noticed.

A 1-year-old sterlet (30 cm) in a 90 cm rectangular glass tank has stayed in the same spot for over 30 minutes with its snout pressed into a corner. Its body sways slightly but it neither moves forward nor turns. Gill movement is slow and sometimes seems to stop. The water is 19°C and water quality is normal.

Which is the most appropriate first action?

1. Gently turn the fish's head away from the corner by hand to face the current, and check whether it swims off and the gills move
2. It is just resting, so leave it undisturbed
3. Drop food in the corner to get it eating and perk it up
4. Tap hard on the tank glass to startle it into moving

AnswerA. Gently turn the fish's head away from the corner by hand to face the current, and check whether it swims off and the gills move

ExplanationSturgeon breathe by swimming continuously to pass water over the gills; when one stops with its head pressed into a corner, no water passes over the gills and it gradually falls into oxygen shortage. Slow gill movement that sometimes stops is a dangerous state. Gently turn the head away from the corner by hand to face the current, and check whether it swims off on its own and the gills move regularly. If it cannot swim, support it horizontally in the current, and see the vet the same day if there is no improvement. It is not resting; left alone, it suffocates. Food is useless if it cannot swim to eat, and fouls the water. Tapping the glass startles it into a wall collision and injures the snout. As the root fix, round off the corners or move to a round tank.

IssuesThe owner did not understand the danger of a sturgeon stopping with its head pressed into a corner of a rectangular tank. Although aware it had been still for over 30 minutes, they mistook it for rest and the response was delayed.

ImprovementStand pipes or boards in all four corners to eliminate them so the fish can circle. Move to a round tank in future. Remember that stopped means danger: if it stays in one spot for more than five minutes, change the direction of its head. Keep a constant current with a flow pump.

Early on an April morning, checking the outdoor 1,500 L round tank, you find two deep triangular puncture wounds on the back of the 3-year-old bester (70 cm), with blood spreading in the water. There are bird footprints on the tank rim and a heron was nearby. The fish is swimming but shudders as if bothered by the wounds, and its gills are moving fast. No net was in place.

Which is the most appropriate response?

1. The wounds will heal naturally, so do nothing and feed as usual
2. Pour antiseptic directly on the wounds to kill bacteria
3. Put out poisoned bait around the tank to drive off the heron
4. Immediately net the whole tank, keep the water clean, photograph the wounds and see the vet the same day

AnswerD. Immediately net the whole tank, keep the water clean, photograph the wounds and see the vet the same day

ExplanationBirds such as herons and crows target fish in outdoor tanks and inflict deep puncture wounds with their beaks. Herons return repeatedly, so first net the whole tank to prevent another attack. Deep punctures can cause internal injury, infection and water mold, and heal slowly in a scaleless sturgeon, so keep the water clean, take photos, and consult an animal hospital that treats fish the same day about treating the wounds. Simply feeding and leaving it lets infection progress. Pouring antiseptic directly damages mucus and skin and fouls the water. Poisoned bait amounts to illegally killing wild birds, is dangerous to other animals and people, and is not an acceptable measure.

IssuesThe outdoor setup had no defense against birds and animals, and attacks by herons and crows were not anticipated. Spring is when herons are most active, and an open water surface is an ideal feeding ground.

ImprovementCover the whole outdoor tank with fine-mesh netting, fixed at a height birds cannot reach from the rim. Raccoons and cats also come, so weight the net down. Every morning, check the fish's body and footprints around the tank, and strengthen defenses at any sign of an attack.

Medium gravel was laid in a 120 cm tank to improve its looks. The 2-year-old sterlet (40 cm) has been seen many times sucking up gravel along with food. For the past three days its belly has looked swollen and hard, and it spits out food after sucking it in. Gravel is mixed in its droppings and it swims heavily. Water quality and temperature are normal.

Which is the most appropriate response?

1. Massage the belly to push the gravel out
2. The gravel will pass eventually, so feed more to push it through
3. Stop feeding, remove the gravel for a bare tank, and see the vet within a few days with photos and video
4. Mix vegetable oil into the food as a laxative

AnswerC. Stop feeding, remove the gravel for a bare tank, and see the vet within a few days with photos and video

ExplanationSturgeon suck up bottom food with a downward-facing mouth, so they easily swallow gravel with it. A swollen, hard belly, spitting out food and heavy swimming are signs that gravel is accumulating in the gut and starting to block it. First stop feeding to reduce the load on the gut, remove the gravel that caused it and go to a bare tank, and consult an animal hospital that treats fish within a few days with photos and video. If it worsens, with rolling over or irregular breathing, switch to seeing the vet the same day. Massaging the belly damages internal organs. More food worsens the blockage and fouls the water. Self-prescribed vegetable oil and the like cause digestive upset and water fouling and have no basis.

IssuesNot knowing the sturgeon's suction feeding, the owner put looks first and laid gravel. They watched it suck up gravel many times without removing it. The swollen belly was noticed for three days before action was taken.

ImprovementKeep the sturgeon tank bare with no substrate. If you must, use a thin layer of fine sand that can be passed if swallowed. Remove any object immediately if the fish is seen sucking it up with food. Check the belly and droppings daily.

A suction cup holding the heater had come loose and dropped to the bottom. In the evening, the 3-year-old bester (70 cm) mistook it for food and sucked it in; part of the cup is visible in its mouth as it opens and closes it. The fish rubs its mouth on the wall trying to spit it out, but it will not come out. The gills are moving but breathing is rapid.

Which is the most appropriate first action?

1. Put a finger in its mouth and forcibly pull the cup out
2. It will swallow and pass it eventually, so leave it
3. Take the fish out of the water, open its mouth and pull it out with pliers
4. Turn off the lights to calm it, watch underwater for a few minutes to see if it spits it out, and if not, see the vet the same day

AnswerD. Turn off the lights to calm it, watch underwater for a few minutes to see if it spits it out, and if not, see the vet the same day

ExplanationSturgeon extend the mouth to suck in food and sometimes suck up dropped parts by mistake. When a foreign object is visible in the mouth, first turn off the lights to reduce stress and watch underwater for a few minutes to see if the fish spits it out on its own. If not, take it to an animal hospital that treats fish the same day to have it removed properly, since an object lodged at the back of the mouth or in the esophagus interferes with breathing and feeding. Forcing it out with fingers or pliers tears the inside of the extensible mouth or the esophagus, causing bleeding and infection. Treatment out of the water adds the dangers of suffocation and drying. Left alone, it may swallow the object, which blocks the gut and can require surgery.

IssuesThe loose suction cup lying on the bottom went unnoticed. The owner did not consider the sturgeon's habit of sucking up dropped parts as food, and relied on an unstable suction cup for mounting.

ImprovementFix equipment to the wall with clamps or bands rather than suction cups, and keep small parts out of the tank. In daily checks look for anything dropped on the bottom and retrieve it at once. Know in advance where to go if a foreign object is swallowed.

A summer night. Mosquito insecticide spray was used for a few seconds in the room with the tank. The mist seems to have entered through gaps in the lid; 30 minutes later the 2-year-old sterlet (40 cm) is shuddering as if in convulsions, spinning and hitting the walls, and working its gills violently. An oily film is floating on the surface.

Which is the most appropriate first action?

1. Remove the surface film, do a 1/3 to 1/2 water change with temperature-matched water, add activated carbon, increase aeration, and see the vet the same day
2. The convulsions are temporary, so turn off the lights and wait until morning
3. Take the fish out into a bucket and leave it for two days until the insecticide clears
4. Medication can neutralize it, so add the recommended dose of fish medication

AnswerA. Remove the surface film, do a 1/3 to 1/2 water change with temperature-matched water, add activated carbon, increase aeration, and see the vet the same day

ExplanationInsecticide spray ingredients are potent neurotoxins for fish, and a scaleless sturgeon absorbs them readily through the skin and gills. Convulsions, spinning, wall collisions and violent gill movement are classic poisoning signs. First remove the surface film, do a larger water change with temperature-matched water to lower the concentration, use activated carbon to adsorb what remains, and increase aeration to secure oxygen, then contact an animal hospital that treats fish the same day. Waiting until morning lets the poisoning progress to death. A bucket is too cramped to swim in and causes suffocation, and the tank contamination remains. Fish medication does not neutralize insecticide and adds to the burden on a weakened fish.

IssuesThe owner did not know the danger of using insecticide spray in the room with the tank, and did not anticipate the mist entering through gaps in the lid. Awareness that a scaleless sturgeon is especially vulnerable to chemicals was also lacking.

ImprovementNever use insecticides, air fresheners or deodorizing sprays in the room with the tank. Control mosquitoes without chemicals, using screens or mosquito nets. Seal gaps in the lid and place the air pump's intake where chemicals cannot reach it. Keep activated carbon and water-change water on hand.

Seeing the fish rubbing its body, you added the recommended dose of an antiparasitic obtained from a koi-keeping acquaintance to the 1,000 L round tank. An hour later, the 4-year-old bester (80 cm) is thrashing violently, arching its body in convulsions, breathing rapidly with its snout out at the surface. Large amounts of mucus are coming off and the water has turned cloudy white.

Which is the most appropriate first action?

1. It was the recommended dose, so there is no problem; take it as proof it is working and continue
2. Assume the dose is insufficient and add more
3. Raise the water temperature to stop the convulsions
4. Do a large water change with temperature-matched water, remove the drug with activated carbon, turn aeration to maximum, and call for an immediate vet visit

AnswerD. Do a large water change with temperature-matched water, remove the drug with activated carbon, turn aeration to maximum, and call for an immediate vet visit

ExplanationSome koi medications are highly toxic to scaleless sturgeon and cause poisoning even at the koi dose. Convulsions, arching, massive mucus shedding and irregular breathing are severe poisoning signs. First do a large water change with temperature-matched water to lower the drug concentration, adsorb it with activated carbon, and turn aeration to maximum to secure oxygen, then call for an immediate vet visit, giving the name of the drug used. Continuing or adding more is fatal. Raising the temperature increases both the drug's toxicity and oxygen consumption, making things worse. Body rubbing does suggest parasites, but diagnosis and drug choice must be left to a vet who treats fish.

IssuesNot knowing the danger of using another species' medication on sturgeon, the owner dosed without a diagnosis. They did not understand that scaleless sturgeon absorb drugs quickly and that even common fish medications and salt easily cause accidents.

ImprovementNever medicate sturgeon on your own judgment; always consult a vet who treats fish. If you see body rubbing, first test the water, take a video and see the vet. Keep activated carbon and water-change water on hand in case of a dosing accident. Always keep the drug container and bring it to the vet.

To treat a small wound on the body, you copied a salt bath method seen online and added a generous amount of table salt to the 90 cm tank without measuring. Twenty minutes later, the 1-year-old sterlet (30 cm) is writhing violently, its mucus is peeling off in strands and drifting in the water, and it is starting to roll onto its side. Gill movement is rapid. The water is 19°C.

Which is the most appropriate first action?

1. This reaction shows the salt is working, so continue as is
2. Lower the salinity with several 1/3 water changes of temperature-matched fresh water, increase aeration, and support it horizontally and see the vet if it rolls over
3. Replace all the water with fresh water at once to remove the salt
4. Add sugar to neutralize the salt

AnswerB. Lower the salinity with several 1/3 water changes of temperature-matched fresh water, increase aeration, and support it horizontally and see the vet if it rolls over

ExplanationScaleless sturgeon are sensitive to osmotic changes; strong salt water strips the skin mucus and causes poisoning signs such as writhing and rolling over. First lower the salinity gradually with several 1/3 water changes of temperature-matched fresh water. Increase aeration to secure oxygen, and if it rolls over, support it horizontally so current passes over the gills; if it does not recover, see the vet the same day. This is not the salt working; continuing kills the fish. Replacing all the water with fresh water at once causes another sudden osmotic change and a second shock. Sugar does not neutralize salt and sharply worsens water quality. Small wounds usually heal with clean water, so avoid self-prescribed salt or medication.

IssuesOnline advice meant for other fish was applied directly to a scaleless sturgeon, and the salt was added without measuring. An excessive treatment for a small wound did more harm than the wound.

ImprovementMake it a rule never to give sturgeon salt or medicated baths on your own judgment. Keep the water clean and monitor wounds, and see the vet if they worsen. Check which species online advice is for, and always consult a vet who treats fish before acting. Know your tank's volume and always measure anything you add.

July. The forecast says a week of extreme heat above 35°C begins tomorrow. The 120 cm tank in a south-facing living room holds a 3-year-old sterlet (50 cm), with only a small fan for cooling. Last summer there was a day the water reached 27°C. The current water temperature is 24°C.

Which is the most appropriate advance preparation?

1. Do nothing and respond once the temperature rises
2. Switching off the heater is enough; nothing else is needed
3. Shade the tank and cool the room with air conditioning, increase aeration, prepare frozen bottles and ice packs, record the temperature twice a day and start cooling once it exceeds 26°C
4. Double the food during the heat to build up its strength

AnswerC. Shade the tank and cool the room with air conditioning, increase aeration, prepare frozen bottles and ice packs, record the temperature twice a day and start cooling once it exceeds 26°C

ExplanationSturgeon are cold-water fish; strain increases above 25°C and 28°C is fatal. As soon as extreme heat is forecast, shade the tank from direct sun, cool the room with air conditioning, increase aeration to secure dissolved oxygen, and put several frozen plastic bottles and ice packs in the freezer. Record the temperature morning and evening and set a rule to start cooling once it exceeds 26°C. This prevents reaching 27°C as it did last year. Responding only after the temperature rises is too late, as high temperature and oxygen shortage progress together. Switching off the heater is not cooling. More food increases oxygen consumption through digestion and leftovers foul the water, which is dangerous at high temperatures.

IssuesDespite the experience of reaching 27°C last year, cooling was still only a small fan and preparation for extreme heat was inadequate. The tank was in a south-facing room, exposed to direct sunlight.

ImprovementInstall a tank chiller so the water can be kept around 20°C year-round. Place the tank on the north side out of direct sun, or shade it. Before summer, prepare ice packs, frozen bottles and a spare fan, and post a temperature log beside the tank. Feed sparingly on extreme heat days.

A typhoon is approaching and an evacuation order is expected tomorrow night. The outdoor 2,000 L round tank holds a 6-year-old bester (over 1 m), which cannot be taken to the shelter. Power outage and flooding are possible. On hand are a portable power station, a battery-powered air pump, netting and a tarp.

Which is the most appropriate response?

1. Put the fish's life first and release it into the nearby river before the water rises
2. Drain all the water, put the fish in a bucket and take it to the shelter
3. Leave the tank as it is, evacuate, and think about it when you return
4. Lower the water level and secure the net, maintain oxygen with the battery-powered air pump and portable power station, secure the tank, evacuate, and return as soon as it is over

AnswerD. Lower the water level and secure the net, maintain oxygen with the battery-powered air pump and portable power station, secure the tank, evacuate, and return as soon as it is over

ExplanationMoving a sturgeon over 1 m is itself a major strain, and taking it to a shelter is not realistic. What can be done is: lower the water level and secure a net over the whole tank to prevent escape in heavy rain, maintain oxygen supply with a battery-powered air pump and portable power station that work in an outage, secure the tank and equipment so they cannot topple, then evacuate with human safety first and return as soon as it is over to check temperature, oxygen and the fish. Release is prohibited under local fisheries regulations and ordinances and harms the ecosystem as an invasive species. A large fish cannot swim in a bucket and suffocates. Evacuating with no preparation means losing the fish to oxygen shortage in an outage or to escape.

IssuesWhen taking on a sturgeon that grows large, the owner had not planned around the fact that it cannot be taken along in a disaster. Preparations for preventing escape and securing oxygen in an outage needed to be in place in advance.

ImprovementOn the assumption the fish stays behind in a disaster, keep an auto-starting battery-powered air pump and a portable power station. Have the tank secured, netting, and mesh on the drain in place at all times. Make a pre-evacuation checklist and share it with the family. Also research who could take the fish if you can no longer keep it.

A January morning. A thin layer of ice has formed on the surface of the outdoor 1,500 L round tank. The water is 3°C. The 5-year-old bester (90 cm) inside swims slowly near the bottom and shows little interest in food. The air pump is running, but you worry that if the ice thickens the surface will be sealed over.

Which is the most appropriate response?

1. Keep an ice-free area open with aeration, do not force heating, feed sparingly, and watch the gills and swimming
2. Add a heater and raise the water to 20°C
3. Hit the ice hard with a hammer to break it
4. It is weak from the cold, so feed more to build up its strength

AnswerA. Keep an ice-free area open with aeration, do not force heating, feed sparingly, and watch the gills and swimming

ExplanationSturgeon are cold-water fish, and a healthy one overwinters fine even around 3°C. Reduced activity and appetite at low temperatures are a normal response. What matters is keeping an ice-free area open with aeration so the surface does not freeze over completely and stop gas exchange, not forcing heating, feeding sparingly since digestion slows, and watching for abnormal gill movement or swimming. Heating to 20°C causes shock from the sudden temperature change and makes high-temperature management from spring onward difficult too. Hitting the ice with a hammer startles the fish with the impact and noise and it crashes into the wall. More food for a fish with slowed digestion leaves uneaten food that fouls the water.

IssuesNot knowing the basic fact that sturgeon tolerate cold well, the owner was anxious about freezing. Knowledge was lacking about the real concerns: gas exchange stopping under complete ice cover and the danger of responses that cause impact.

ImprovementIn winter, place an air stone near the surface to keep an opening in the ice and prevent complete freezing. When the water drops below 5°C, reduce feeding to once every few days. Make abnormal swimming and gill movement the winter observation points and keep logging the thermometer. Do not use a heater.

A major earthquake struck in the middle of the night; nearly half the water in the indoor 150 cm tank spilled, and a power outage has stopped the pump and air pump. The 4-year-old sterlet (55 cm) is starting to roll onto its side in the shallow water that remains. The water is 18°C. The water supply is still working. On hand are a battery-powered air pump, dechlorinator and a flashlight.

Which is the most appropriate first action?

1. Take the fish out, wrap it in a wet towel and wait for dawn somewhere safe
2. Prioritize repairing the tank and deal with the fish later
3. Collect the spilled water from the floor and put it back in the tank
4. After confirming your own safety, start the battery-powered air pump, add temperature-matched dechlorinated water to a depth the fish can swim in, and watch the gills and swimming

AnswerD. After confirming your own safety, start the battery-powered air pump, add temperature-matched dechlorinated water to a depth the fish can swim in, and watch the gills and swimming

ExplanationFirst confirm the safety of yourself and your family, and check for fallen objects and broken glass. Then put the battery-powered air pump into the tank, whose oxygen supply has stopped, and to fix the shallow water it cannot swim in, add temperature-matched dechlorinated water to a depth where the fish can swim level. Support the rolling fish horizontally so current passes over the gills, watch its swimming and gill movement, and see the vet the same day if it does not recover. Wrapped in a wet towel, the gills do not work and it suffocates. Prioritizing tank repair means oxygen shortage wins the race. Water spilled on the floor contains dirt and detergent and fouls the water if returned.

IssuesThe risk of water spilling in an earthquake, dropping the level so a sturgeon that must keep swimming could no longer swim, had not been considered. Securing the tank, sealing the lid and preparing oxygen for an outage were inadequate.

ImprovementSecure the tank with anti-seismic mats and fixings so it cannot move, and seal the lid to reduce water sloshing out. Keep the water level at least 10 cm below the rim. Prepare a battery-powered air pump that starts automatically in an outage and stored water, and keep a flashlight and dechlorinator near the tank.

June. For a house move, a 4-year-old bester (80 cm) must be driven three hours to the new home. The water was 21°C the day before. Available are a large cooler box, thick bags, an oxygen cylinder, ice packs and a battery-powered air pump. The car interior is expected to reach nearly 30°C. It has been fed as usual up to the day before.

Which is the most appropriate transport method?

1. Feed it well just before leaving, and carry it in a bucket of water on the passenger seat
2. Fast it from the day before, put tank water and oxygen in the cooler box, prevent warming with ice packs, keep it dark, and match temperature before releasing it on arrival
3. Water is heavy, so wrap it in a wet towel for the trip
4. Load the whole tank into the car with the water still in it

AnswerB. Fast it from the day before, put tank water and oxygen in the cooler box, prevent warming with ice packs, keep it dark, and match temperature before releasing it on arrival

ExplanationThe biggest risks in transporting a large sturgeon are oxygen shortage and high temperature. Fast it from the day before to reduce waste and ammonia during transport, put tank water in the cooler box and fill it with oxygen, supplement with the battery-powered air pump, prevent the water warming from the car's heat with ice packs, and keep it dark to reduce agitation. On arrival, match temperature for 30 minutes or more before release and watch its swimming. Feeding just before leaving fouls the water with waste and increases oxygen consumption. A bucket is too cramped to swim in and spills dangerously. In a wet towel the gills do not work, it suffocates and the skin is damaged. Moving the whole tank risks breakage, and sloshing water throws the fish against the walls.

IssuesOxygen consumption during transport and the rise in car temperature were underestimated. Normal feeding continued up to the day before, with no fasting preparation. The transport procedure was not confirmed in advance.

ImprovementFast the fish for two days before transport and travel in the cool hours of early morning or night. Prepare an oxygen cylinder, battery-powered air pump and several ice packs, and check temperature and the fish en route. Set up the tank at the destination in advance and bring it to the same temperature.

Three weeks after cutting a hand on the sturgeon's scutes, the wound has not healed and has become a small reddish-purple lump, with similar lumps appearing in a line toward the wrist. Pain is mild but they are gradually increasing. Over-the-counter antiseptic has made no difference, and tank cleaning has continued bare-handed. There is no fever.

Which is the most appropriate response?

1. It is a rash unrelated to the fish, so apply an over-the-counter anti-itch cream
2. It will heal on its own, so leave it
3. Switch to gloves for tank work, see a dermatologist, and be sure to mention the cut came from a fish tank
4. The fish is the cause, so get rid of the sturgeon

AnswerC. Switch to gloves for tank work, see a dermatologist, and be sure to mention the cut came from a fish tank

ExplanationA wound exposed to tank water that does not heal and forms reddish-purple lumps lining up toward the wrist is the classic course of a skin infection by nontuberculous mycobacteria (fish tank granuloma). It does not respond to ordinary antiseptics, and the history of tank contact is important for diagnosis, so see a dermatologist and be sure to mention that the cut came from the sturgeon's scutes and your habit of tank work. Switch to waterproof gloves for future work and wash hands with soap afterward. Anti-itch cream or neglect lets it progress, with more lumps and longer treatment. There is no need to get rid of the fish; gloves and hand washing prevent it. People with weak immune systems need particular care.

IssuesUnaware of the danger of cuts from scutes and the infection risk of tank work with a wounded hand, the owner kept cleaning bare-handed. A non-healing wound was left for three weeks and the decision to see a doctor was delayed.

ImprovementAlways do tank work in waterproof gloves, and use thick gloves when handling the fish. Avoid tank work when you have a cut on your hand. Wash hands with soap afterward. If a tank-related wound has not healed in two weeks, see a dermatologist and mention the tank.

You have decided to bring home a second sterlet (25 cm) from the shop. The existing 120 cm tank holds a healthy 3-year-old (50 cm). The new fish looks normal, but it was sharing a tank with other fish at the shop. A spare 60 cm tank and filter are available.

Which is the most appropriate response?

1. It looks healthy, so put it straight into the main tank
2. Put it into the main tank together with the bag water and let them swim together
3. Add fish medication to the main tank as a precaution before introducing it
4. Quarantine it in the spare tank for 2–4 weeks, use separate equipment, and move it to the main tank if nothing is wrong

AnswerD. Quarantine it in the spare tank for 2–4 weeks, use separate equipment, and move it to the main tank if nothing is wrong

ExplanationA new fish can bring in parasites or bacteria even when it looks healthy, and a shop fish that shared a tank with other fish is especially high risk. Quarantine it in the spare tank for 2–4 weeks, check gill movement, body surface, appetite and swimming daily, keep nets and buckets separate for each tank, and move it to the main tank if nothing is wrong. If signs such as body rubbing or one gill held shut appear during quarantine, see the vet. Putting it straight in can infect the healthy existing fish. The bag water may contain pathogens, so never add it to the main tank. Preventive medication is a heavy burden on scaleless sturgeon, and dosing without a diagnosis should be avoided.

IssuesThe owner did not fully understand the importance of quarantining new arrivals and tried to judge health by appearance alone. The risk of a fish that shared a tank with other fish at the shop was not considered.

ImprovementAlways quarantine new fish in a spare tank for 2–4 weeks. Color-code equipment by tank and never share it. Write down the observation points for quarantine and check them daily. Move to the main tank only after matching temperature and water quality, and without adding the bag water.

During the Sunday water change, you started the hose siphon by sucking on it, and tank water rushed into your mouth; you swallowed a little. The tank holds a 3-year-old sterlet (50 cm), and leftover food and droppings had accumulated. Afterward a fishy taste lingered, and the next day you have mild stomach pain and diarrhea.

Which is the most appropriate response?

1. Rinse your mouth right away, switch to a siphon that does not need mouth suction, and if diarrhea or stomach pain persists or fever develops, see a doctor and mention you swallowed tank water
2. Fish water is harmless, so carry on with water changes without worrying
3. Take antidiarrheal medicine and watch; no need to see a doctor
4. The fish carries disease, so get rid of all the fish in the tank

AnswerA. Rinse your mouth right away, switch to a siphon that does not need mouth suction, and if diarrhea or stomach pain persists or fever develops, see a doctor and mention you swallowed tank water

ExplanationTank water contains many bacteria from leftover food and droppings, and swallowing it can cause stomach pain and diarrhea. Rinse your mouth right away, and from now on use a pump-type or self-priming siphon so you never suck by mouth. Since stomach pain and diarrhea appeared the next day, see a doctor if the symptoms persist, fever develops or there is blood in the stool, and mention that you swallowed tank water to speed the diagnosis. Fish water is not harmless; swallowing it can make you ill. Suppressing it with antidiarrheals can delay clearing the bacteria, so avoid self-treatment. The fish does not carry any special disease and there is no need to get rid of it.

IssuesThe owner did not recognize that starting a siphon by mouth is dangerous and had no proper water-change equipment. Work was done with leftover food and droppings accumulated, so the water was especially dirty.

ImprovementChange water with a pump-type siphon or a submersible pump and never suck by mouth. Wash hands with soap after work, and rinse off any tank water that splashes the face. Remove leftover food daily to keep water-change water cleaner. Make a habit of telling medical staff about the tank when you are unwell.

Last week parasites were found on the koi in the garden pond, which are under treatment. The same net and bucket have continued to be used for cleaning the indoor sturgeon tank (2-year-old sterlet, 40 cm). This morning the sturgeon is rubbing its body on the bottom and barely opening one gill. Water quality and temperature are normal.

Which is the most appropriate response?

1. Add the same medication as the koi to the sturgeon tank
2. Water quality is normal, so do nothing
3. Rinsing the net lightly in tap water is enough, so keep sharing it
4. Stop sharing equipment immediately, keep separate sets per tank, film the sturgeon's symptoms and see the vet within a few days

AnswerD. Stop sharing equipment immediately, keep separate sets per tank, film the sturgeon's symptoms and see the vet within a few days

ExplanationSharing a net and bucket from a koi pond with parasites carries parasites and eggs into the sturgeon tank. Body rubbing and holding one gill shut are classic parasite signs, and the route and timing match. First stop sharing equipment and provide a dedicated set for each tank, film the symptoms, and have the fish examined at an animal hospital that treats fish within a few days. Some koi medications are highly toxic to scaleless sturgeon, and reusing them leads to poisoning accidents. Parasites are a separate problem even when water quality is normal, and left alone gill damage progresses. A light rinse in tap water does not remove parasite eggs.

IssuesThe owner did not recognize the infection risk of sharing equipment between keeping areas, and failed to separate equipment when parasites were found on the koi. They also did not know that sturgeon are drug-sensitive, which limits treatment options.

ImprovementKeep nets, buckets and hoses dedicated to each keeping area and color-coded. Dry equipment from a tank with disease after use and never use it elsewhere. Work from healthy tanks to sick ones, and wash hands afterward. Get sturgeon abnormalities examined early.

6 a.m. The 3-year-old sterlet (50 cm) in the indoor 150 cm tank is lying belly-up on the bottom. It was swimming normally last night. It does not flee when approached and the barbels do not move. The gill covers seem to be moving slightly, but you are not sure. The water is 22°C and the air pump is running.

Which is the most appropriate first action?

1. Judge it dead and remove it
2. Drop food in front of it and see if it reacts
3. Check the gill covers closely; if they are moving, gently right the fish, support it in front of the current, increase aeration and test the water
4. Tap on the tank glass to rouse it

AnswerC. Check the gill covers closely; if they are moving, gently right the fish, support it in front of the current, increase aeration and test the water

ExplanationA sturgeon upside down on the bottom is in critical condition, but if the gill covers are moving even slightly it is alive and may recover. First look closely at whether the gill covers open and close; if they do, gently right the fish, support it in front of the current so water passes over the gills, and turn aeration to maximum to secure oxygen. At the same time, test temperature, ammonia and nitrite to look for a cause, and if it cannot swim on its own within 30 minutes, see the vet immediately. Declaring it dead without checking gill movement loses a life that could be saved. A weakened fish will not respond to food, which only fouls the water. The shock of tapping the glass adds further strain to a weakened fish.

IssuesThe overnight change went unnoticed, and there was no water-quality log to help identify a cause. Knowing in advance how to check consciousness and breathing (gill cover movement, barbel response, level body) would have allowed a calm judgment.

ImprovementRemember that a sturgeon's life and breathing are checked by the opening and closing of the gill covers. Understand that rolling over or being upside down is an emergency, and practice the routine of supporting it horizontally in the current. Find a fish-treating animal hospital with after-hours emergency service in advance and post its number beside the tank.

A 2-year-old sterlet (45 cm) wedged between a pipe and the wall was rescued by removing the pipe. But the fish lies on the bottom without swimming and the gill covers are barely moving. The body is not yet stiff, and the tail moves slightly when touched. The water is 20°C and the air pump is running.

Which is the most appropriate first action?

1. It is already too late, so remove it and bury it
2. Hold the fish horizontally and move it slowly forward in front of the current so water passes from mouth to gills, turn aeration to maximum, and continue until the gills start moving
3. Take it out of the water and press on its chest for cardiac massage
4. Blow into its mouth for artificial respiration

AnswerB. Hold the fish horizontally and move it slowly forward in front of the current so water passes from mouth to gills, turn aeration to maximum, and continue until the gills start moving

ExplanationA sturgeon trapped and unable to swim gets no water over its gills and is near respiratory arrest from oxygen shortage, but if the body is not stiff and the tail responds there is room for resuscitation. Fish resuscitation is not cardiac massage but getting water over the gills so oxygen is taken up. Hold the fish horizontally and move it slowly forward in front of the current so water flows from the mouth over the gills, turn aeration to maximum to raise dissolved oxygen, and continue for several minutes to tens of minutes until the gill covers move on their own. Once it swims on its own, watch it in front of the current and see the vet the same day. Taking it out of the water stops the gills working, and pressing on the chest damages internal organs. Blowing into the mouth does nothing, as fish cannot take oxygen from air.

IssuesA gap wide enough for a sturgeon that cannot back up to enter head-first was left between the pipe and the wall. Time passed before discovery, and oxygen shortage progressed to the brink of respiratory arrest. Not knowing how to resuscitate a fish, the owner tried to apply human CPR.

ImprovementFix all pipes and equipment flush against the wall with zero gaps. Remember fish resuscitation as: support it horizontally and pass water over the gills, and maximize oxygen; share the routine with the family. Morning and evening checks catch trapping early, and inspect likely trap spots every time.

A collision with the glass wall has split the snout of a 4-year-old bester (80 cm) deeply, and the water in the 1,000 L tank is turning faintly red. Bleeding continues after 15 minutes; the fish swims slowly but stops now and then. Gill movement is rapid. The water is 21°C and quality is normal; it is 10 p.m. and the local animal hospital is closed.

Which is the most appropriate first action?

1. Take the fish out and apply pressure to the snout with gauze to stop the bleeding
2. Hold a tissue against the bleeding spot underwater
3. Replace all the water to dilute the blood
4. Turn off the lights to reduce stress, increase aeration, keep the water clean, and if bleeding continues, see the vet the same day and prepare for transport

AnswerD. Turn off the lights to reduce stress, increase aeration, keep the water clean, and if bleeding continues, see the vet the same day and prepare for transport

ExplanationFish bleeding cannot be stopped by pressure underwater; gauze or tissue will not stop it and only strips mucus and invites infection. What you can do is turn off the lights to calm the fish and reduce blood pressure and movement, increase aeration to offset the oxygen deficit from blood loss, and keep the water clean to prevent the wound becoming infected. A deep laceration still bleeding after 15 minutes needs a vet's treatment, so contact an animal hospital that treats fish the same day and prepare for transport with a bag, oxygen and ice packs. Out of the water it is fatal through suffocation and drying. A full water change shocks a weakened fish with a sudden change in water quality.

IssuesA large fish was kept in a glass tank with corners, leaving the risk of a deep snout laceration from collision unaddressed. Lacking the knowledge that fish bleeding cannot be stopped like a land animal's, the owner might have hesitated over what to do.

ImprovementMove large fish to a round tank or round off the corners to reduce impact. Remember fish bleeding as: rest, oxygen, clean water, transport. Keep the contact details of a fish-treating animal hospital and a transport bag, oxygen and ice packs on hand. Turn lights on in stages to prevent collisions.

A 3-year-old bester (70 cm) needs to be seen for hemorrhagic spots on its body and must be driven 40 minutes to the animal hospital. The vet has asked you to bring the fish. The air temperature is 28°C. On hand are thick bags, a large cooler box, ice packs, a battery-powered air pump and towels.

Which is the most appropriate transport method?

1. Put tank water in the cooler box, supply oxygen with the battery-powered air pump, prevent warming with ice packs, keep it dark and minimize jolting
2. Wrap it in a wet towel and carry it on your lap
3. Carry it in a bucket of tap water with the lid closed so it does not spill
4. A large fish cannot be transported, so go to the hospital with just a video

AnswerA. Put tank water in the cooler box, supply oxygen with the battery-powered air pump, prevent warming with ice packs, keep it dark and minimize jolting

ExplanationThe main risks in transporting a large sturgeon are oxygen shortage, high temperature and impact. Tank water in the cooler box avoids sudden changes in water quality and temperature; supply oxygen with the battery-powered air pump, and with the air at 28°C use ice packs to prevent the water warming. Closing the lid keeps it dark and calm, and avoiding hard braking minimizes jolting. On arrival follow the vet's instructions, and on returning home match temperature before putting it back. In a wet towel the gills do not work and it suffocates on a 40-minute trip. Tap water damages the gills with chlorine, a bucket is too cramped to swim in, and a closed lid also cuts off oxygen. If the vet has asked for the fish, it is needed for the examination; a video alone cannot give a diagnosis.

IssuesNo thought had been given in advance to how to transport a large fish, which could have caused panic at the time of the visit. The owner needs to understand that managing oxygen and temperature during transport is a matter of life and death.

ImprovementKeep a transport kit ready: cooler box, battery-powered air pump, ice packs and thick bags. Find a fish-treating animal hospital in advance and discuss transport methods. Fast the fish the day before transport so it does not foul the water. Bring a thermometer and check it during the trip.

1 a.m. The 5-year-old sterlet (55 cm) in the indoor 120 cm tank is gulping at the surface with its snout out and sometimes tilting sideways. The water is 24°C and the air pump is running. You turned aeration to maximum and did a 1/3 water change, but after an hour it is still starting to roll over. The emergency (after-hours) animal hospital is an hour's drive away, and whether it treats fish is unknown.

What is the most appropriate decision at this point?

1. Nothing more can be done, so sleep and wait for morning
2. Fish cannot be seen at an after-hours emergency, so give up
3. It is rolling over, so add fish medication and wait until morning
4. Phone the after-hours emergency hospital to ask whether they treat fish; if yes, prepare for transport and go; if not, decide to see a fish-treating vet first thing in the morning and keep up oxygen and horizontal support

AnswerD. Phone the after-hours emergency hospital to ask whether they treat fish; if yes, prepare for transport and go; if not, decide to see a fish-treating vet first thing in the morning and keep up oxygen and horizontal support

ExplanationRolling over that does not improve after an hour of oxygen supply and a water change is a serious sign warranting after-hours emergency care. After-hours hospitals that treat fish are limited, so first phone to ask whether they can see it; if so, prepare oxygen and ice packs and transport it. If not, decide to go to a fish-treating hospital first thing in the morning, and until then keep aeration at maximum, lights off to reduce stress, and the rolled-over fish supported horizontally with current over the gills. Doing nothing and waiting risks suffocation overnight. Giving up on the assumption it cannot be seen is premature. Fish medication with no known cause adds strain to a rolled-over fish and interferes with diagnosis.

IssuesContact details for an after-hours emergency that treats fish had not been researched in advance, forcing a decision in the middle of the night. First aid was done, but no criteria had been set for the next step of seeking care.

ImprovementConfirm in advance which animal hospitals treat fish and whether they offer after-hours service, and post the numbers beside the tank. Set criteria for an immediate vet visit: no improvement an hour after first aid, rolling over, gills nearly stopping. Keep a transport kit ready so you can move even in the middle of the night.

A 4-year-old bester (75 cm) has not eaten for three days, and this morning its gills are moving fast and red spots have appeared on its body. When you phone an animal hospital that treats fish, they ask you to provide information about the tank before coming in. On hand are a thermometer, test strips and a smartphone.

Which is the most appropriate set of information to prepare before the visit?

1. Only the fish's name and the name of the shop where it was bought
2. Only a disease name you looked up online and the medication you added
3. Water temperature, ammonia and nitrite readings, tank volume and fish length, video of the symptoms, date of the last water change and what it has been fed
4. Only one photo of the fish and the owner's phone number

AnswerC. Water temperature, ammonia and nitrite readings, tank volume and fish length, video of the symptoms, date of the last water change and what it has been fed

ExplanationFish disease usually stems from water quality and environment, and the vet builds a diagnosis and treatment plan from information about the tank. What is needed is the water temperature, ammonia and nitrite readings, tank volume and fish length (for judging dosing and stocking density), a video of the symptoms (gill movement and swimming cannot be reproduced in the exam room), the date of the last water change and what it has been fed, and whether any new fish or equipment has been added. If possible, bring a small sample of tank water. The shop's name or the fish's name does not help diagnosis. An online disease name and self-prescribed medication mislead the diagnosis and complicate treatment, so if you have added any medication, bring the container and say so honestly. A single photo cannot convey abnormal gill movement or swimming.

IssuesNo regular log of temperature and water quality was kept, so gathering information had to start from scratch at the time of the visit. A habit of filming symptoms and keeping records would have allowed accurate information to be given to the vet on the phone.

ImprovementUse a notebook or app to log temperature, water quality, water-change dates, feeding amounts and any abnormalities daily. Make it a habit to film first whenever something seems wrong. Make a checklist of information to bring to the vet and keep a small bottle ready for a water sample.