Loach case method: 50 questions

Late October, morning. Two of the four 3-year-old pond loaches in a 45 cm tank have salt-grain-like white spots scattered over their bodies and fins. They are also seen rubbing against the driftwood. Nights have turned cold and no heater is installed. The thermometer reads 17°C, 5°C lower than last week.

What is the most appropriate first action?

1. Rub the white spots off with a wet finger, then return the fish to the tank
2. Raise the water temperature to 30°C all at once to kill the parasites
3. Install a heater, raise the temperature 1–2°C per day to 26–28°C, and do a 1/3 water change
4. Add tropical-fish ich medication at double the label dose to cure it for sure

AnswerC. Install a heater, raise the temperature 1–2°C per day to 26–28°C, and do a 1/3 water change

ExplanationWhite spots plus body rubbing are classic ich, triggered by lowered immunity after a sudden temperature drop. Because the ich parasite tends to stop multiplying in warmer water, the safe basic response is to raise the temperature gradually, 1–2°C per day, to 26–28°C and do a 1/3 water change to reduce free-swimming parasites. Jumping straight to 30°C causes temperature shock that kills weakened fish. The spots sit within the skin and cannot be rubbed off; rubbing strips the mucus and opens the door to fungus. Loaches have tiny scales and are easily affected by medication; a double dose carries a high risk of fatal toxicity. If you do medicate, use a separate container, consult a shop or vet, and set the dose carefully. If there is no improvement, consult a fish vet or specialist shop the same day.

IssuesThe owner did not check the water temperature at the change of season and let a 5°C drop in one week go unaddressed. They also lacked the knowledge that loaches get ich too, and did not notice until it had spread to two fish.

ImprovementCheck the thermometer every morning and keep changes within 2°C per day. In autumn, install a heater early or move the tank somewhere the room does not get cold. Make a habit of inspecting every fish's skin and barbels at the evening feeding.

An August evening. In a room without air conditioning, six pond loaches in a 60 cm tank rise to the surface every few minutes to gulp air, and come right back up after returning to the bottom. Normally it was a few times an hour. The thermometer reads 31°C. There is no air pump, and the filter flow is weak.

What is the most appropriate first response in this situation?

1. Intestinal breathing is normal behavior, so ignore it and watch
2. Drop ice straight into the tank to cool the water quickly
3. Set aeration to maximum and lower the temperature with a cooling fan and small, repeated water changes
4. Replace all the water with fresh, cold water

AnswerC. Set aeration to maximum and lower the temperature with a cooling fan and small, repeated water changes

ExplanationIntestinal breathing is normal, but a sharp rise in frequency with the fish not staying at the bottom is a sign of low dissolved oxygen. At 31°C the water holds less oxygen while the fish need more, so oxygen deficiency worsens. The correct response is to supply oxygen with aeration first, then lower the temperature with a cooling fan and small, repeated water changes, keeping the drop within 2–3°C per day. Ice dropped straight in chills the water locally and causes temperature shock. A full water change abruptly alters water quality and wipes out the bacteria, making things worse. Just watching means oxygen falls further overnight, and the whole tank can be dead by morning. If there is no improvement, consult a specialist shop the same day.

IssuesThere were no measures at all against summer heat, and no aeration was installed. The owner did not know the normal rate of intestinal breathing, so recognizing the abnormality was nearly delayed.

ImprovementKeep a cooling fan and aeration running all summer and hold the temperature at or below 28°C. Observe and remember the normal frequency of intestinal breathing, and treat an increase as oxygen deficiency. Consider moving the tank to an air-conditioned room.

A June evening at feeding time. One pond loach has several red spots on its belly, the abdomen is swollen, and its skin looks rough. It does not respond to food. The last water change was 3 weeks ago, and leftover food has piled up on the sand. The other four tank mates look healthy.

What is the most appropriate first action?

1. Assume the red spots are abrasions from jumping out and just watch
2. Isolate it in a separate container with fresh water at the same temperature for a salt bath; in the main tank, remove leftovers and do a 1/3 water change
3. Crush human antibiotics into the main tank to treat everything at once
4. Replace all the water and wash the substrate with detergent to disinfect it

AnswerB. Isolate it in a separate container with fresh water at the same temperature for a salt bath; in the main tank, remove leftovers and do a 1/3 water change

ExplanationRed spots, abdominal swelling and raised scales are classic Aeromonas infection, caused by poor water quality from skipped water changes and leftover food. The correct response is to isolate the sick fish and monitor it in a 0.3–0.5% salt bath while removing leftovers from the main tank and doing a 1/3 water change to cut off the cause. Just watching lets the ulcers spread into holes and infect the other fish. Human medicine is of unknown type and dose for fish and kills the beneficial bacteria too. A full water change and detergent disinfection cause abrupt water changes, and detergent residue causes poisoning. If ulcers spread or several fish are affected, consult a fish vet or specialist shop the same day, and always medicate in a separate container.

IssuesWater changes were skipped for 3 weeks and leftover food was left in place. The assumption that loaches are hardy led to lax water management and created a breeding ground for disease. No quarantine container was ready, so the initial response was delayed.

ImprovementDo a 1/3 water change on a fixed day each week and feed only what is eaten in a few minutes. Remove leftovers with a pipette the next morning. Keep a quarantine box and air pump ready so any abnormal fish can be separated immediately.

9 p.m. on a scorching July day. In a room without air conditioning, a 2-year-old pond loach in a 45 cm tank has a white, soggy area around its mouth and the edge of its tail fin is frayed and rotting. Nothing was wrong at yesterday's feeding. The thermometer reads 30°C, and another fish in the same tank is starting to show a white tail tip. The owner has no cooling fan.

What is the most appropriate first action?

1. Scrape off the white areas with a cotton swab, return the fish to the tank and watch
2. Raise the water temperature with a heater to suppress bacterial activity
3. Fin rot regenerates on its own, so do nothing
4. Isolate the affected fish; cool the main tank with a fan and do a 1/3 water change

AnswerD. Isolate the affected fish; cool the main tank with a fan and do a 1/3 water change

ExplanationRapid white rotting of the mouth and fins is classic columnaris, which progresses fast in warm water and is highly contagious. The correct response is to isolate the affected fish to stop the spread, cool the main tank to 28°C or below with a fan, and do a 1/3 water change to reduce bacterial density. Scraping the white areas strips the mucous membrane and makes it worse. Raising the temperature makes the bacteria even more active, and the fish can die within 1–2 days. The disease moves too fast for waiting on natural regeneration. After isolating, consult a specialist shop or fish vet the same day; if medicating, dose carefully for a tiny-scaled fish like a loach.

IssuesThe water was left at 30°C on a scorching day, creating the conditions for columnaris to multiply. The sudden change from a normal appearance the day before was also partly due to not knowing how fast this disease progresses.

ImprovementIn summer, check the thermometer morning and evening and run a cooling fan whenever it passes 28°C. Inspect fins and mouth at every evening feeding. Keep a quarantine container and air pump ready so an abnormal fish can be isolated the same day.

A January morning. In a tank placed in an entryway at 12°C room temperature, a 5-year-old pond loach is floating near the surface with a swollen belly and bobs back up when it tries to dive. No red spots or white spots on the skin. Last night it was fed the usual amount and ate it. The water is 10°C.

What is the most appropriate first action?

1. Stop feeding for 2–3 days, stabilize the temperature, lower the water level, and consult if there is no improvement
2. Increase food to aid digestion and get the gut moving
3. Push it down to the bottom by hand and bury it in the sand so it stops floating
4. Use a heater to raise the water to 25°C at once to boost metabolism

AnswerA. Stop feeding for 2–3 days, stabilize the temperature, lower the water level, and consult if there is no improvement

ExplanationAt low temperatures digestion slows, and feeding the usual amount produces gas in the intestine, causing bloating and floating. The correct response is to stop feeding to rest the gut, stabilize the temperature, lower the water level so intestinal breathing and defecation are easier, and monitor. More food worsens the indigestion. Pressing by hand damages the mucus and skin, and the stress can be fatal. A sudden jump to 25°C is dangerous temperature shock; if raising, keep it within 2°C per day. If there is no improvement in 2–3 days, or red spots or raised scales appear, Aeromonas is possible, so consult a fish vet or specialist shop the same day.

IssuesThe fish was fed the same amount as in summer despite its metabolism being slowed by cold winter water. The owner did not know to adjust feeding to temperature, and placing the tank in a cold entryway at 12°C added further strain.

ImprovementBelow 15°C, feed a small amount every 2–3 days; below 10°C, stop almost entirely. Use sinking rather than floating food and stick to amounts eaten within a few minutes. In winter, move the tank to a room with little temperature swing.

May. The barbels of three pond loaches in a 30 cm tank are clearly shorter than before, and one has whitish, rotting skin around its mouth. The substrate is coarse Oiso gravel and water is changed about once a month. They eat well but poke at the bottom less. The water is slightly cloudy white.

What is the most appropriate first action?

1. Barbels fall off naturally, so ignore it
2. Add a nutritional supplement to the water to grow the barbels back
3. Change water more often, switch the substrate to fine sand, and isolate the fish with the rotting mouth
4. Replace all the water, sterilize the gravel with boiling water and put it back

AnswerC. Change water more often, switch the substrate to fine sand, and isolate the fish with the rotting mouth

ExplanationBarbels shortening or rotting is a classic sign of abrasion from coarse gravel plus bacterial infection from poor water quality. The correct response is to raise water changes to weekly to improve the water, switch the substrate to fine, rounded sand to remove the cause, and isolate the fish with the rotting mouth to monitor it in a salt bath. Barbels are vital organs for finding food and do not fall off naturally. Supplements do not address the cause. A full water change and boiling-water sterilization abruptly alter the water and bacteria and weaken the fish further. If the rot spreads, consult a specialist shop or fish vet the same day. In a clean environment, barbels regenerate.

IssuesThe owner used a coarse substrate unsuited to loaches and changed water only once a month. Not knowing that barbels are a health barometer, they missed the change.

ImprovementUse fine sand such as paddy sand or bottom sand and keep to a weekly 1/3 water change. Make a habit of checking barbel length and the mouth at feeding. Cloudy water signals deteriorating quality, so change water as soon as it turns cloudy.

A March morning. Three days ago a striped loach that had jumped through a gap in the lid was found on the floor and returned to the tank. This morning, a white cotton-like growth is attached to the scrape on its flank from the fall and is spreading slightly. The fish is swimming and eating. Water is 18°C.

What is the most appropriate first action?

1. Scrape the white cotton off with a net, then return the fish to the tank
2. Isolate in clean water at the same temperature with a 0.3% salt bath; if it spreads, ask about medication
3. Raise the water temperature to 30°C at once to kill the fungus
4. It is eating, so do nothing and wait for it to heal naturally

AnswerB. Isolate in clean water at the same temperature with a 0.3% salt bath; if it spreads, ask about medication

ExplanationWhite cotton on a wound is fungal infection, which takes hold where drying and abrasion have stripped the mucus. The correct response is to isolate the fish in clean water at the same temperature with a 0.3% salt bath to restore the mucus and prevent secondary infection. Scraping the cotton widens the wound and scatters spores through the tank. A sudden temperature rise causes temperature shock in loaches. Left alone, the fungus invades the muscle and the fish dies. If the salt bath does not halt the spread, consult a specialist shop or vet and medicate in a separate container. Loaches are sensitive to medication, so dose more cautiously than the label. Also seal the lid gap to remove the cause of recurrence.

IssuesThe wound from the jump was not inspected and was left for 3 days. The root cause was the unsealed lid gap, so the jumping accident itself had not been prevented.

ImprovementAfter returning a fish that jumped out, inspect its wounds daily for a week. Keep a quarantine container and salt on hand, and isolate immediately if cotton or redness appears. Plug lid and cord gaps with filter wool or covers, and keep the water level 5 cm or more below the rim.

Three golden pond loaches were added to a 30 cm tank set up only 4 days earlier. Two days later their whole bodies look faintly cloudy white and strands of mucus drift in the water. They rub against the bottom and intestinal breathing has become frequent. The filter is running, but no bacterial starter was used. The water smells slightly fishy.

What is the most likely cause, and the first response?

1. Treat as ich: raise the temperature to 28°C and medicate
2. Mucus is normal, so leave it
3. Treat as parasites: wipe the skin with a cotton swab
4. Treat as ammonia and nitrite buildup in a newly set up tank: change 1/3 to half the water with water at the same temperature

AnswerD. Treat as ammonia and nitrite buildup in a newly set up tank: change 1/3 to half the water with water at the same temperature

ExplanationIn a newly set up tank the filter bacteria have not developed, so within days of adding fish, ammonia and nitrite accumulate. Excess mucus, cloudy skin, rubbing and frequent intestinal breathing are signs of membrane irritation from toxins and oxygen deficiency. The correct response is to first change 1/3 to half the water with dechlorinated water at the same temperature to lower the concentration, then continue small daily changes. Unlike ich, this is not spot-shaped, so heating or medicating only adds irritation. Left alone, the fish die within days. Wiping with a swab strips the membrane and makes it worse. Golden loaches have pale coloring that makes skin changes easy to see, so use that advantage and observe daily. If there is no improvement, test the water and consult a specialist shop.

IssuesThe owner did not know that a tank needs time for filter bacteria to establish and added fish on day 4. The amount of food and number of fish were also too much for a new tank, speeding the decline in water quality.

ImprovementRun a new tank for 2–4 weeks, then start with just a few fish. Keep ammonia and nitrite test kits and test every few days during startup. Feed sparingly for the first month and do small, frequent water changes.

September. Five pond loaches bought from a pet shop were added to the main tank along with the water from their bag. The main tank holds goldfish and loaches that have lived there healthily for 3 years. Four days later, one newcomer is rubbing against the driftwood, and a single white spot is visible on one of the long-term loaches.

What is the most appropriate response at this point?

1. Observe all fish, old and new; raise the temperature gradually and do a 1/3 water change; isolate the worst-affected fish
2. Return only the newcomers to the shop and leave the main tank as it is
3. The bag water caused it, so replace all the water and the substrate
4. It is only one white spot, so do nothing and watch for a week

AnswerA. Observe all fish, old and new; raise the temperature gradually and do a 1/3 water change; isolate the worst-affected fish

ExplanationWith no quarantine period for the new fish and the bag water poured in, ich was brought into the main tank. Since the established fish already show symptoms, the correct response is to treat the whole tank: raise the temperature 1–2°C per day, do a 1/3 water change to reduce free-swimming parasites, and isolate fish with severe symptoms. Returning only the newcomers leaves the parasites in the tank. Replacing all the water and substrate weakens the fish through abrupt change and loss of bacteria, and still does not fully remove the parasite. Ich multiplies explosively within days, so a week of waiting lets it spread to everything. If there is no improvement in a week, consult a specialist shop or fish vet; if medicating, do it carefully in a separate container.

IssuesNew fish were put straight into the main tank without quarantine, bag water included. There was a lack of awareness of the risk of introducing pathogens and no quarantine container was prepared.

ImprovementObserve new fish in a separate container for 1–2 weeks before adding them. Never put bag water in the main tank, and acclimate by drip method over at least an hour. Keep a quarantine container, air pump and thermometer as a set.

December. Three pond loaches are kept in an unheated indoor tank at 8°C. For 3 days all of them have stayed buried in the sand, barely emerging and not responding to food. Brushing a little sand aside shows their bodies bend and move and their gills are moving. No skin abnormalities, and the water is clear.

What is the most appropriate response in this situation?

1. Treat it as illness: dig them out of the sand and give a salt bath
2. Treat it as reduced activity from cold water: hold off on feeding, prevent freezing, maintain water quality and watch
3. Remove all the sand so they cannot burrow and will eat
4. Use a heater to bring the water up to 25°C overnight to make them active

AnswerB. Treat it as reduced activity from cold water: hold off on feeding, prevent freezing, maintain water quality and watch

ExplanationLoaches are cold-blooded; below 10°C their metabolism drops and they burrow into the sand and stay still. If the body moves, the gills move, the skin is normal and the water is clear, this is a normal way of passing the winter. The correct response is to hold off on feeding, keep the room from freezing, maintain water quality and watch. Digging them out for a salt bath weakens them with needless stress. Removing the sand takes away their shelter and further exhausts fish that cannot move in the cold. A jump to 25°C overnight causes temperature shock, and they may eat when unable to digest, filling the gut with gas. However, lying on the side without moving, a stiff body, or red spots are abnormal; consult the same day.

IssuesThe owner did not know that loaches burrow and go still in cold water and nearly mistook it for illness. They had no checking procedure to distinguish reduced activity from disease.

ImprovementCheck the water temperature daily in winter and move the tank to a warmer room so it never drops below 5°C. Below 10°C, stop feeding almost entirely and give only a small amount on warm days. Learn the method of brushing aside a little sand to check body response and gill movement.

A September afternoon with a typhoon approaching. Five pond loaches that normally stay buried by day are all swimming vigorously around the tank, going up and down to the surface. Water is 24°C, skin is normal, intestinal breathing is slightly increased but they do return to the bottom. The water was changed yesterday and is clear.

What is the most appropriate response to this behavior?

1. Treat it as a normal reaction to falling air pressure; check that the lid is secure and watch
2. Treat it as oxygen deficiency and do a full water change to add oxygen
3. Turn the lights up bright so they are easier to observe and to calm the panic
4. It is a sign of illness, so give all fish a salt bath

AnswerA. Treat it as a normal reaction to falling air pressure; check that the lid is secure and watch

ExplanationLoaches are sensitive to falling air pressure and swim actively before typhoons and thunderstorms; they were once used to forecast the weather. With no problem in temperature, skin or water quality, and intestinal breathing still followed by a return to the bottom, this is a normal reaction. However, excited fish are most prone to jumping out, so the correct response is to check that the lid is secured and gap-free and then watch. A full water change causes real problems through abrupt changes in water quality. Brighter lighting excites them further and causes leaping. A salt bath is needless stress. On the other hand, if frequent intestinal breathing without returning to the bottom or body rubbing is also present, oxygen deficiency or illness is possible, so add aeration and observe.

IssuesThe owner did not know that loaches react to pressure changes and nearly mistook normal behavior for illness. They were also not prepared for the higher risk of jumping out during excitement.

ImprovementBefore stormy weather, check the lid weight and gaps and keep the water level 5 cm or more below the rim. Write the criteria that separate normal behavior from warning signs (skin, frequency of intestinal breathing, water quality) on paper and post it beside the tank.

In a community tank of goldfish and pond loaches, the goldfish developed ich, so last night ich medication was added directly to the tank at the label dose. This morning the goldfish are swimming normally, but two loaches are lying on the bottom, gills moving but unable to swim. They are shedding large amounts of mucus and the water is cloudy.

What is the most appropriate first action?

1. It proves the medicine is working, so continue for the full course
2. The effect is weak, so add more medicine to raise the concentration
3. Move the loaches to clean, medication-free water at the same temperature, increase aeration, and keep them dark and quiet
4. Immediately return the loaches with the goldfish to a fully water-changed tank and never use medication again

AnswerC. Move the loaches to clean, medication-free water at the same temperature, increase aeration, and keep them dark and quiet

ExplanationLoaches have tiny scales that let medication enter the body easily, so even the label dose used for goldfish can poison them. Lying flat with heavy mucus is a sign of drug toxicity. The correct response is to move them to clean, medication-free water at the same temperature, increase aeration, keep them dark and quiet, and wait for recovery. Continuing or adding more will kill them. Treat the goldfish's ich in a separate container and dilute the medication in the main tank with water changes. A full change would also shock the goldfish, so do it in several 1/3 changes. When medicating loaches, consult a specialist shop or fish vet and dose more cautiously than the label. If they do not recover, consult the same day.

IssuesThe owner did not know loaches are sensitive to medication and put the label dose directly into a community tank. Skipping the basic step of isolating sick fish for treatment led to the poisoning.

ImprovementAlways move sick fish to a separate container for medicated baths and never medicate the main tank. For tiny-scaled fish including loaches, set the dose after consulting a specialist shop or vet. Keep a quarantine set with a treatment container, air pump and thermometer.

7 a.m. on an April morning. A pond loach is found on the hardwood floor beneath the tank. Its skin is nearly dry and dusty, but it wriggles slightly when touched. Nothing was wrong at lights-out last night, and the lid had a gap of about 1 cm at the corner where the cord passes through.

What is the most appropriate first action?

1. Rinse the dust off with tap water, then return it to the tank
2. Gently wet it with tank water, mucus and all; return it to the tank, increase aeration, and keep it dark and quiet
3. It is dry, so assume it is dead and bury it
4. Rub the dust off by hand and feed it right away to build its strength

AnswerB. Gently wet it with tank water, mucus and all; return it to the tank, increase aeration, and keep it dark and quiet

ExplanationLoaches can also breathe through the skin and intestine, and it is not unusual for one to recover after hours out of water as long as the body is moist. Wriggling means it is alive, so the correct response is to gently wet it with tank water, mucus and all, return it to the tank, increase aeration, keep it dark and quiet, and not touch it until it starts moving. Do not use tap water; the chlorine irritates the weakened membrane. Rubbing by hand strips mucus and skin and opens the door to fungus. Feeding a weakened fish causes indigestion and gas in the gut. After returning it, inspect daily for a week for wounds, white cotton and redness; if they appear, isolate and give a salt bath. Seal the gap that caused the jump the same day.

IssuesA 1 cm gap was left at the corner where the lid meets the cord. The owner did not realize a loach's thin, flexible body can slip through even a 1 cm gap, and the water level was also high.

ImprovementPlug every gap where cords and tubing pass through with filter wool or covers, and weigh down the lid. Keep the water level 5 cm or more below the rim. Make a habit of counting fish first thing in the morning, and never give up on a fish found on the floor; return it to water and watch for a response.

A February evening. A 1-year-old striped loach in a 30 cm tank with coarse Oiso gravel has several red, scraped wounds on its belly and around its mouth. It keeps rubbing itself against the gravel trying to burrow. Some wounds are oozing a little blood; water is 16°C. It is eating, and water quality is maintained with weekly changes.

What is the most appropriate first action?

1. Apply human antiseptic to the wounds and return it to the tank
2. Remove all the gravel and keep it in a bare tank until the wounds heal
3. Move it to a quarantine container with fine sand for a 0.3% salt bath, and switch the main tank substrate to fine sand
4. Bleeding stops on its own in water, so leave the environment as it is

AnswerC. Move it to a quarantine container with fine sand for a 0.3% salt bath, and switch the main tank substrate to fine sand

ExplanationUsing coarse gravel for a loach that burrows scrapes the belly and mouth raw, and fungus or Aeromonas enters through the wounds. The correct response is to move it to a quarantine container with fine sand for a 0.3% salt bath to restore mucus and prevent infection, and to switch the main tank substrate to fine, rounded sand such as paddy sand to remove the cause. Human antiseptic damages the fish's membranes and contaminates the water. Removing all the sand leaves the fish stressed and unable to burrow; it thrashes against the glass and gets new wounds. If the environment is not changed, wounds keep multiplying. Bleeding itself stops in clean water, but if cotton-like growth or red patches spread, consult a specialist shop or fish vet the same day.

IssuesThe owner chose a coarse substrate unsuited to the loach's burrowing habit. Even on finding the wounds, they did not realize the substrate was the cause and thought only of treating the wounds.

ImprovementLay 3–5 cm of fine, rounded sand such as paddy sand or bottom sand. Choose rocks and driftwood without sharp edges. Keep spare sand so the quarantine container can get a thin layer too, and check the skin and belly for wounds at the weekly water change.

November, the week after installing a heater. A pond loach is found wedged in the gap between the heater and the glass. Once pulled out, it has a white, discolored burn-like mark on its flank with peeling skin. The heater has no guard and there was a 1 cm gap between it and the glass.

What is the most appropriate first action?

1. Switch off the power, then free it gently; rest it in a separate container with a salt bath and fit a guard on the heater
2. Burns should be cooled, so put it in a container of ice water
3. Peel off the loose skin with your fingers to tidy it up, then return it
4. Remove the heater immediately and keep them unheated through winter

AnswerA. Switch off the power, then free it gently; rest it in a separate container with a salt bath and fit a guard on the heater

ExplanationLoaches squeeze into narrow gaps, and they can get wedged between an unguarded heater and the glass and burned. First switch off the power to prevent electric shock and further burns, then free the fish gently, give a 0.3–0.5% salt bath in a separate container to restore mucus and prevent secondary infection, and keep it dark and quiet. Fit a guard on the heater and leave no gaps. Ice water weakens the fish through temperature shock. Peeling skin with fingers widens the wound and invites infection. There is no problem using a heater as long as no gaps are left; an unheated tank dropping below 5°C is more dangerous. If white cotton or ulcers appear, consult a specialist shop or fish vet the same day.

IssuesThe owner installed an unguarded heater against the wall without considering the loach's habit of entering narrow gaps. No inspection was done after installation, and the fish may have been wedged for close to a week before being noticed.

ImprovementAlways use a guarded heater and fix it in a position with no gap against the glass or driftwood. Fit a sponge on the filter intake. For a week after installing any equipment, check the head count and each fish's location daily and inspect for gaps where a fish could get stuck.

May. A pond loach kept with two fairly large goldfish has a torn tail fin with a red edge. During the day the goldfish were seen chasing and pecking the loach after it emerged from the sand. The loach is staying still in a corner of a tank with no hides. Water quality is good.

What is the most appropriate first action?

1. Trim the torn fin with scissors before returning it
2. Separate the loach with a divider or a separate container, let it regenerate in clean water, and add hides
3. Withhold food from the goldfish for a while to punish them
4. It can swim with a torn fin, so keep them together as they are

AnswerB. Separate the loach with a divider or a separate container, let it regenerate in clean water, and add hides

ExplanationTorn fins regenerate on their own in clean water, but continued chasing adds wounds, and fungus or columnaris enters through them. The correct response is to separate the loach from the goldfish with a divider or separate container, let it regenerate in clean water, and add several hides such as clay pipes or driftwood for when it returns. Cutting the fin causes bleeding and infection. Withholding food does not change the goldfish's pecking; hunger makes it worse. Left alone, chronic stress reduces appetite and leads to illness. If the fin edge turns white and rots or grows cotton during regeneration, isolate and give a salt bath; if no improvement, consult a specialist shop or fish vet.

IssuesThe loach was kept with large goldfish in a tank with no hides, so it had nowhere to escape when it came out of the sand by day. The owner underestimated tank-mate compatibility and the importance of hides.

ImprovementLimit tank mates to gentle, small-mouthed fish and provide at least one hide per fish. Lay 5 cm of fine sand so they can burrow. Keep a divider on hand and separate the fish the same day if chasing is seen. Check fin condition at every evening feeding.

August. A pond loach was scooped with a coarse-mesh net for a water change; it thrashed violently in the net and its barbels tangled in the mesh. On removal, one barbel is broken and there is slight bleeding from the mouth. The remaining loaches are still in the tank and were also due to be moved.

What is the most appropriate response at this point?

1. Quickly scoop the rest with the same net and finish the job
2. Broken barbels do not regenerate, so apply antiseptic to the wound
3. Rest the injured fish in clean water, and move the rest by scooping them in a container with their water
4. If netting does not work, grip them by hand to move them

AnswerC. Rest the injured fish in clean water, and move the rest by scooping them in a container with their water

ExplanationA loach's slippery, mucus-covered body thrashes violently in a net, and in coarse mesh the barbels and body get tangled and injured. The correct response is to rest the injured fish in clean water at the same temperature, let the bleeding stop naturally in the water, and move the rest not with a net but by scooping them in a container with their water. Continuing with the same net adds injuries. Barbels regenerate in a clean environment, so antiseptic is unnecessary and only damages the membranes. Gripping by hand makes the fish thrash and fall and strips its mucus. In any case, a weekly 1/3 water change does not require moving the fish. If white cotton appears on the wound, isolate and give a salt bath; if it spreads, consult a specialist shop or fish vet.

IssuesThe owner performed the unnecessary task of netting the fish at every water change, and used a coarse-mesh net. Understanding of the loach's body structure and handling was lacking.

ImprovementDo water changes with the fish in the tank using a gravel cleaner, and move fish only when necessary by scooping them in a container with their water. If a net is needed, use a soft, fine-mesh net near the surface and keep it brief. Watch the barbels and mouth for a week after any move.

11 p.m. on an October night. On the check before lights-out, a young 4 cm striped loach is found with its tail sucked against the intake pipe of the canister filter installed last month, unable to pull free despite wriggling. The intake has no sponge and the flow is set fairly strong. The tip of the tail fin is drawn in and red.

What is the most appropriate first action?

1. Grab the tail by hand and pull it free
2. Switch off the filter to stop the suction, wait for it to come free on its own, then rest it in a separate container
3. Turn up the suction to push it through all at once
4. It will free itself, so leave it until morning

AnswerB. Switch off the filter to stop the suction, wait for it to come free on its own, then rest it in a separate container

ExplanationA fish held against an intake cannot escape while suction continues, and the tail fin tears or the skin is damaged. Switch off the filter first to stop the suction, and the fish frees itself. The correct response is then to rest the freed fish in a separate container of clean water at the same temperature and watch the wound. Pulling by hand while suction continues tears the tail fin and strips mucus. Increasing the flow draws the body further in and kills it. Leaving it until morning causes exhaustion. To prevent recurrence, fit a sponge on the intake and reduce the flow for juveniles and small species. If white cotton or redness spreads on the tail, isolate and give a salt bath; if no improvement, consult a specialist shop or fish vet.

IssuesDespite having a small juvenile with weak swimming ability, the owner used a strong-flow filter with no sponge on the intake. There was insufficient consideration of the loach's habit of entering narrow spaces along the bottom and walls.

ImprovementAlways fit a sponge on the intake, and for juveniles and small species choose a low-flow sponge or undergravel filter. For several days after changing equipment, check the fish's locations and the area around the equipment, including at night.

June. A pond loach has gone head-first into a narrow crack in the driftwood, with only the rear half of its body outside, thrashing violently. After 30 minutes it is still stuck, and its flank is rubbed raw with mucus coming off white. The driftwood is siliconed to the bottom and cannot easily be removed.

What is the most appropriate first action?

1. Grab the tail and pull it out by force
2. Turn off the lights and leave it overnight so it can free itself
3. Take the driftwood out of the tank, and under water widen the crack or split the wood to release the fish gently
4. Push the body through with tweezers so it comes out the other side

AnswerC. Take the driftwood out of the tank, and under water widen the crack or split the wood to release the fish gently

ExplanationLoaches enter narrow holes, and once head-first into a crack they cannot back out and get stuck. The more it thrashes, the more mucus is lost and the more wounds it gets, so it must be freed quickly. The correct response is to detach the driftwood, and in a container of water widen the crack or split the wood to release the fish without force, then rest it in a separate container of clean water. Pulling the tail can tear the body or injure the spine. Left overnight it becomes exhausted and dies. Pushing with tweezers injures the head and barbels. After release, check daily that fungus does not appear where mucus was lost; if cotton or redness appears, give a salt bath, and if no improvement, consult a specialist shop or fish vet.

IssuesThe owner used driftwood with a crack just wide enough for a loach to enter and fixed it so it could not be removed. They had no habit of checking the layout for gaps a fish could get stuck in.

ImprovementChoose driftwood and rocks without narrow cracks or holes; any hole should be either comfortably wide enough to pass through or too narrow to enter. Attach decor so it can be removed. Fill narrow gaps during a monthly layout inspection.

July. A red swamp crayfish the child caught was put into the pond loach tank 2 days ago. This morning one loach has a deep pincer wound on its back with the skin split open and muscle visible. The crayfish is under the driftwood, threatening another loach with its claws.

What is the most appropriate first action?

1. Move the crayfish to a separate container; isolate the injured loach for a salt bath and consult about the deep wound the same day
2. Release the crayfish in a nearby river and return the loach to the tank to watch
3. Apply human ointment to the wound before returning it to the tank
4. Feed the crayfish more so it is full and stops attacking

AnswerA. Move the crayfish to a separate container; isolate the injured loach for a salt bath and consult about the deep wound the same day

ExplanationCrayfish are predators that grab bottom-dwelling fish like loaches with their claws; keeping them together always causes harm. First move the crayfish to a separate container to remove the danger, then give the injured loach a 0.3–0.5% salt bath in clean water at the same temperature to prevent infection. A deep wound with muscle exposed carries a high risk of bacterial infection and fungus, so the correct response is to consult a specialist shop or fish vet the same day. The red swamp crayfish is a conditionally designated Invasive Alien Species, and releasing it into the wild is prohibited by law. Human ointment dissolves in water, damages the membranes and does nothing for fish. Even a full crayfish pinches anything that moves.

IssuesThe owner did not know crayfish prey on bottom-dwelling fish and kept them together. They were also unaware that keeping invasive species involves legal rules, and were careless about introducing collected animals.

ImprovementLimit loach tank mates to gentle small fish; keep crustaceans and large fish in a separate tank. Before adding any collected animal, check predator relationships and legal regulations. Keep a quarantine container, salt and the contact details of a consultant ready for deep wounds.

A March morning, the day after sharp-edged lava rock was added in a layout change. A 4-year-old pond loach in a 60 cm tank has one eye clouded white with slight swelling around it. The other eye is normal; swimming is a little unsteady but it responds to food. Water quality is good at 20°C, and the four other tank mates show nothing abnormal.

What is the most appropriate first action?

1. Eye cloudiness is ich, so raise the temperature and medicate
2. Remove the sharp rock; isolate in clean water for a salt bath, and consult the same day if it worsens
3. Apply eye drops, then return it to the tank
4. It can live with one eye, so do nothing

AnswerB. Remove the sharp rock; isolate in clean water for a salt bath, and consult the same day if it worsens

ExplanationClouding and swelling in only one eye most likely means injury from hitting the sharp rock. The correct response is to remove the rock that caused it, give a 0.3% salt bath in a separate container of clean water at the same temperature to prevent secondary infection, and consult a specialist shop or fish vet the same day if it worsens. If both eyes are affected or spots also appear on the body, ich or bacterial infection is possible, but with one eye only, suspect injury and avoid needless heating or medication. Human eye drops do not work under water, and taking the fish out of the water is a heavy burden. Left alone, bacteria enter the eyeball and lead to blindness or systemic infection. A nocturnal loach can find food with its barbels and live with one eye, but treatment is still needed.

IssuesThe owner used sharp-edged rock in the layout without considering that a startled loach could run into it. They also did not appreciate that fish are unsettled right after a layout change and accidents are more likely then.

ImprovementChoose rounded rocks and driftwood without edges, and run your hand over them before adding them to check for sharp parts. For several days after a layout change, dim the lights to settle the fish and check their eyes and skin daily.

10 p.m. on a September night. The moment the room light was switched on, a pond loach was startled, thrashed around the tank and slammed into the edge of a ceramic ornament installed that day. It has a split wound on its flank that keeps oozing blood, and the surrounding water looks faintly red. It is starting to lie on its side on the bottom, but its gills are moving. Water is 25°C.

What is the most appropriate first action?

1. Press a tissue on the wound to stop the bleeding, then return it
2. Remove the ornament; place it in a quarantine container of clean water at the same temperature with strong aeration, keep it dark and quiet, and give a salt bath
3. Apply an over-the-counter styptic to the wound, let it dry, then return it to the tank
4. Replace all the tank water with tap water only so no germs enter the wound

AnswerB. Remove the ornament; place it in a quarantine container of clean water at the same temperature with strong aeration, keep it dark and quiet, and give a salt bath

ExplanationBleeding in fish is hard to stop out of water; it stops naturally when the fish rests in clean water. The correct response is to remove the ornament that caused it, place the fish in a quarantine container of clean water at the same temperature with strong aeration, keep it dark and quiet, and protect the mucus with a 0.3–0.5% salt bath. Pressing with a tissue strips mucus and skin, and the longer the fish is out of water the weaker it gets. Human styptic is harmful to fish skin, and the act of drying is itself fatal. Chlorine in tap water strongly irritates damaged membranes, and a full water change causes shock. If it keeps lying on its side, the wound is deep with muscle visible, or bleeding has not stopped by the next day, consult a specialist shop or fish vet the same day.

IssuesA sharp-edged ornament was added and the fish was startled at night, right after installation when it was unsettled. The owner did not know that fish bleeding is managed in water and nearly applied land-animal first aid, which is dangerous.

ImprovementChoose ornaments without sharp edges, and for several days after installation dim the lights and do not approach suddenly. Keep a quarantine container, air pump and salt ready, and remember that bleeding means rest in clean water. Never switch on lights suddenly near the tank at night.

2 a.m. On the way to the bathroom in a dark hallway, something soft was stepped on underfoot. With the light on, a pond loach is on the floor, and the middle of its body where it was stepped on looks slightly flattened. The body wriggles weakly and the mouth is moving. The tank lid had slid open.

What is the most appropriate first action?

1. Push the flattened part back into shape by hand, then put it in the tank
2. Assume it cannot be saved and deal with it in the morning
3. Wet it with tank water and return it to the tank; increase aeration, keep it dark and quiet, and monitor until morning
4. Put it in a basin of lukewarm water right away to warm it up

AnswerC. Wet it with tank water and return it to the tank; increase aeration, keep it dark and quiet, and monitor until morning

ExplanationIf the body and mouth are moving, it is alive. The extent of internal damage from being stepped on cannot be judged from outside, so the correct response is to wet it with tank water, mucus and all, return it to the tank, increase aeration, keep it dark and quiet, and leave it untouched until morning. Loaches also breathe through the skin and intestine, so mild damage can recover. Pushing the flattened part back by hand worsens internal injury. Left until morning, a fish that could have been saved dies of drying. Lukewarm water causes temperature shock. If by morning it cannot swim, the belly swells or it keeps lying on its side, consult a specialist shop or fish vet the same day. Fix the slipped lid the same day.

IssuesThe owner went to bed with the lid slid open and did not notice the jump. They placed the tank in a dark hallway without considering the risk of stepping on a fish on the floor at night.

ImprovementWeigh down the lid and check its position and the head count before bed. Do not place the tank in a walkway. Light your footing when passing the tank at night. Keep the water level 5 cm or more below the rim to reduce jumping.

May. While cleaning the substrate with a gravel cleaner, a striped loach buried in the sand was sucked through the hose and dropped into the drain bucket. The bucket holds dirty water, sand and feces. The loach is moving on the bottom of the bucket, but it seems to have scraped itself inside the hose and its mucus is white.

What is the most appropriate first action?

1. Pour the dirty bucket water, fish and all, back into the tank
2. Scoop it from the bucket in a container with water, move it to a container of tank water, then return it, and watch the wounds for several days
3. Grab it by hand, rinse it under tap water and return it to the tank
4. The bucket water is dirty, so just pour fresh tap water in on top

AnswerB. Scoop it from the bucket in a container with water, move it to a container of tank water, then return it, and watch the wounds for several days

ExplanationDrain-bucket water contains feces and ammonia, and prolonged exposure leads to poisoning or infection. The correct response is to scoop the fish in a container with water, move it first to a separate container filled with tank water, then return it to the tank, and watch for several days for white cotton or redness where the hose scraped it. Pouring the dirty water back returns the waste you just removed. Grabbing by hand makes it thrash and fall and strips mucus, and chlorine in tap water damages the membranes. Pouring tap water into the bucket weakens it through chlorine and temperature difference. If cotton appears on the wound, isolate and give a salt bath; if no improvement, consult a specialist shop or fish vet.

IssuesThe owner forgot the loach's burrowing habit and siphoned without checking the sand. They also had little awareness of the danger of leaving a fish in the drain bucket for a long time.

ImprovementBefore cleaning the substrate, confirm the head count and where fish are buried, and fit a net over the end of the gravel cleaner. Keep the drain bucket in sight during work and always check inside afterward. Build a head count into the water-change routine.

A November evening. On returning home, the tank lid is askew and the pet cat has its front paws on the rim. Counting the loaches, there are 2 instead of 3. There are water marks on the floor nearby but no fish in sight. The room is 15°C and dry. The cat's mouth is wet.

What is the most appropriate first action?

1. Scold the cat, then check on the remaining two
2. Shut the cat in another room, search under furniture and in gaps around the tank, and return any fish found to water even if dry to check for a response
3. It cannot be found, so give up and search tomorrow
4. To protect the remaining two, move the tank right now to the bathroom where the cat cannot get in

AnswerB. Shut the cat in another room, search under furniture and in gaps around the tank, and return any fish found to water even if dry to check for a response

ExplanationA loach that has jumped out wriggles across the floor and often ends up under furniture or in dark gaps. The correct response is to first shut the cat in another room to prevent further harm, then search under furniture, behind cords and along walls around the tank, and return any fish found to the tank after wetting it with tank water, even if dry, and watch for a response. Loaches breathe through the skin and intestine and can recover even hours later if still moist. Scolding does not change the cat's behavior and wastes search time. Waiting until tomorrow means certain death by drying. Suddenly moving the tank stresses the remaining fish and causes spills and more accidents. A fish the cat carried may have deep wounds, so once found, isolate it in a salt bath and consult the same day.

IssuesIn a home with a cat, the tank was kept with no weight or lock on the lid. The cat could reach the tank while the owner was out, and there was no preparation for the dual risk of jumping and predation.

ImprovementSecure the lid with a weight or clips, and place the tank where the cat cannot climb or in a room that can be closed off. Make a habit of counting fish when you get home and before bed. Decide in advance that any fish found on the floor goes back into water, and keep a quarantine container ready.

A Sunday afternoon in June. A 5-year-old reached into the tank, grabbed a pond loach with bare hands, and dropped it on the floor when it thrashed. The drop was about 80 cm. The loach is wriggling violently on the floor, with grip marks and stripped mucus visible on its body. The child is crying and trying to grab it again.

What is the most appropriate first action?

1. Stop the child; gently scoop the fish with wet hands or a container and return it to the tank; increase aeration and keep it dark and quiet
2. It is thrashing on the floor, so wrap it in a dry towel before returning it
3. Let the child grab it again and put it back themselves
4. Rinse its body under tap water, return it to the tank and feed it right away

AnswerA. Stop the child; gently scoop the fish with wet hands or a container and return it to the tank; increase aeration and keep it dark and quiet

ExplanationThe correct response is to first stop the child from grabbing it again, gently scoop the fish with wet hands or a container, return it to the tank, increase aeration, keep it dark and quiet, and not touch it until it starts moving. A loach's mucus is its protective layer; wrapping it in a dry towel strips the mucus and damages the skin, opening the way for fungus and Aeromonas. If the child grabs it again it may fall again, risking internal injury. Chlorine in tap water irritates the weakened membranes, and feeding right after a shock causes indigestion. After returning it, watch the grip marks for several days for white cotton or redness; if it cannot swim or the belly swells, consult a specialist shop or fish vet the same day.

IssuesThe child could reach into the tank, and the rule that fish are not to be touched had not been taught. The lid was not secured, and there was no household agreement on how children should interact with the animals.

ImprovementSecure the lid and teach the child repeatedly to look but not touch. When they want closer contact, an adult scoops the fish in a container with water for observation. Place the tank at a height children cannot easily reach, or in a room with a door.

Moving day in August. Six pond loaches were put in a single plastic bag with tank water, tied with almost no air, and placed on the back seat. Two hours after departure, with the car interior at 35°C, all of them are gasping at the surface and two are starting to lie on their sides. The destination is still an hour away.

What is the most appropriate response in this situation?

1. Without opening the bag, cool it by aiming the air conditioner vent directly at it
2. Only an hour to go, so just hurry on as is
3. Buy ice at a convenience store and put it directly in the bag
4. Open the bag and refill it with air, shield it from the heat in a foam box or cooler bag, and split the fish into several bags if possible

AnswerD. Open the bag and refill it with air, shield it from the heat in a foam box or cooler bag, and split the fish into several bags if possible

ExplanationWith little air in the bag and heat reducing dissolved oxygen, six fish in one bag are suffocating. The correct response is to open the bag and refill it with plenty of fresh air, protect it from the hot car interior with a foam box or cooler bag, and if possible split the fish into several bags to reduce the number per bag. Oxygen does not increase unless the bag is opened. Blasting the air conditioner directly causes a sudden temperature change and overchills the bag. Ice placed directly inside chills locally and causes shock. Another hour as is, and the fish lying on their sides die. On arrival, move them to fresh water at the same temperature, increase aeration, and keep them dark and quiet to recover. For any fish that does not recover, consult a specialist shop or fish vet the same day.

IssuesThe basics of transport, plenty of air, a few fish per bag, and an insulated box, were skipped. The owner did not anticipate the heat of a car interior in midsummer and created a situation where oxygen deficiency and high temperature struck at once.

ImprovementFor transport, fill bags with 1 part water to 2 parts air, 2–3 fish per bag, and keep them dark in a foam box. In summer tape ice packs to the outside of the box; in winter, hand warmers on the outside. On trips over 3 hours, check the bags along the way.

A January night. The glass tube of the tank heater is found broken. Small bubbles are rising at the surface and the heater cord is still live. The four pond loaches are huddled motionless in a corner of the tank. The power outlet is directly below the tank, and the surrounding floor is slightly wet.

What is the most appropriate first action?

1. Scoop the fish out by hand first, then unplug the heater
2. Reach into the water, lift the heater out and unplug it
3. Without touching the tank water and avoiding the wet floor, cut the power at the breaker or outlet, then remove the heater
4. The heater still works, so keep using it broken and replace it tomorrow

AnswerC. Without touching the tank water and avoiding the wet floor, cut the power at the breaker or outlet, then remove the heater

ExplanationA tank with a broken, live heater can electrocute anyone who puts a hand in the water. The correct response is to avoid touching the water and the wet floor, cut the power completely at the breaker or outlet first, and only then remove the heater. Reaching in to scoop the fish first risks electrocuting yourself, and the fish cannot be saved either. Touching the outlet while standing on a wet floor is also dangerous. Using it broken leads to electrical leakage, fire and electrocution of the fish. After cutting the power, check how the fish respond; move any that do not move to clean water at the same temperature, increase aeration and let them rest. An unheated tank in winter is dangerous, so maintain the temperature the same day with a new guarded heater or by warming the room.

IssuesThe outlet was directly below the tank, where water could reach it. The heater's glass tube was not inspected, and the owner did not know the procedure for a broken heater. Preparedness for the dangers of electricity and water was lacking.

ImprovementPlace outlets higher than the tank or well away from it, and leave slack in cords so water cannot run down them. Use a power strip with ground-fault protection and inspect the heater's glass tube and mounting monthly. Keep a spare heater and remember that cutting the power comes first in an emergency.

An April evening. A 30 cm tank on an unstable storage cube tipped and fell, and the glass shattered. Glass shards and sand are scattered across the floor, and three pond loaches are wriggling in the puddle. One has a cut on its belly from the glass. There is no spare tank, but there is a bucket.

What is the most appropriate first action?

1. Clear away all the glass first, then look for the fish
2. Fill the bucket with dechlorinated water and add aeration; move the fish first with wet hands, and put the injured one in a separate container
3. Pour tap water straight into the bucket and put all the fish in together
4. Put the fish back in the puddle on the floor and go buy a new tank

AnswerB. Fill the bucket with dechlorinated water and add aeration; move the fish first with wet hands, and put the injured one in a separate container

ExplanationFish on the floor weaken from drying as time passes, so rescuing them comes first. The correct response is to fill a bucket with dechlorinated water, add aeration, move the fish with wet hands, and put the injured one in a separate container with a salt bath to prevent infection. Clearing the glass first lets the fish dry out. Chlorine in tap water strongly irritates weakened membranes. The puddle on the floor is shallow, the glass and sand injure the fish, and they dry out while you shop for a tank. Take care not to cut your own hands on the glass during the rescue. After moving them, keep them dark and quiet, and consult a specialist shop or fish vet the same day about the deeply wounded fish. Watch the skin for cotton or red patches for several days.

IssuesA filled tank was placed on an unstable storage cube. The owner did not realize that even a 30 cm tank weighs over 15 kg with water and sand, and had no spare container or aeration ready.

ImprovementPlace the tank on a dedicated stand or a sturdy one with a stated load rating, and check that it is level. Keep a spare bucket, air pump and dechlorinator as an emergency kit. For earthquakes, anchor the stand and lower the water level.

May. During a big clean, the tank decor was being washed in the bathroom when a striped loach, supposedly safe in a bucket, jumped out and was found wriggling on the drain grate. The gaps in the grate are narrow, but it is trying to push its head through. The bathroom floor is wet.

What is the most appropriate first action?

1. It can survive in the sewer if it goes down the drain, so leave it
2. Spray it with the shower to push it away from the drain
3. Scoop it up immediately with a container of dechlorinated water, or with wet hands if there is no time, and put a lid on the bucket from now on
4. Remove the grate and search inside the drain pipe

AnswerC. Scoop it up immediately with a container of dechlorinated water, or with wet hands if there is no time, and put a lid on the bucket from now on

ExplanationLoaches have slim bodies and push head-first into narrow gaps, so one can get into the drain pipe even through the grate. The correct response is to scoop it up immediately with a container of dechlorinated water, or with wet hands if there is no time, return it to the container, and from then on keep a lid on the holding bucket. In the drain it dies from chlorine, detergent and sewage, so leaving it is not an option. Spraying with the shower startles it into fleeing down the drain, and chlorine in tap water damages its membranes. Removing the grate widens the opening and guarantees it falls in. After returning it, watch for stripped mucus and cotton on wounds; if anything abnormal appears, isolate and give a salt bath.

IssuesThe holding bucket had no lid and the jumping habit was not considered. Work was done in a bathroom, a hazardous place with drains and detergents, and the fish's holding container was placed out of sight.

ImprovementCover the holding bucket with a lid or net and keep the water level low. Keep the fish container in sight during cleaning and cover the drain grate with a net. Wash decor somewhere other than the bathroom, away from the fish.

A July evening. Half the tank water was changed in a hurry, and only afterward did the owner realize plain tap water had been used. Ten minutes later, five pond loaches are swimming violently around the tank with repeated intestinal breathing, and two are starting to lie on the bottom with their gills pumping hard. Dechlorinator is on hand.

What is the most appropriate first action?

1. Add the label dose of dechlorinator directly to the tank, mix, increase aeration and watch
2. Do another full change with tap water to dilute it
3. Move all the fish to a bucket of tap water
4. Add salt to protect the membranes; that neutralizes the chlorine

AnswerA. Add the label dose of dechlorinator directly to the tank, mix, increase aeration and watch

ExplanationChlorine in tap water directly damages the gills and membranes, and tiny-scaled fish like loaches are affected especially quickly. Thrashing, frequent intestinal breathing and lying flat are classic chlorine poisoning. Adding the label dose of dechlorinator directly to the tank neutralizes the chlorine within seconds, making it the fastest and most reliable fix. Then increase aeration and let them rest. A full change with tap water only adds chlorine and worsens it. Moving them to a bucket of tap water is dangerous for the same reason. Salt does not neutralize chlorine. Fish with damaged gills stay weak for several days, so keep them dark and quiet; if any keep lying on their sides, consult a specialist shop or fish vet the same day.

IssuesEven in a hurry, the basic water-change steps were skipped. The root cause was having no habit of dechlorinating in a bucket and no system for preparing change water in advance.

ImprovementDraw change water into a bucket the day before, add dechlorinator and match the temperature. Post the steps, dechlorinate, check temperature, then pour, beside the tank. Keep the dechlorinator right next to the tank and always use it, even in a hurry.

A September night. Bothered by mosquitoes in the room with the tank, the owner sprayed aerosol insecticide for a few seconds near the tank, whose lid was open. Thirty minutes later, three pond loaches are swimming as if convulsing and are going still at the surface with their mouths open. The window is closed and the smell of the spray lingers in the room.

What is the most appropriate first action?

1. Insecticide is said to be harmless to fish, so just watch
2. Move the fish to a bucket in another room until the smell is gone
3. Turn off the lights and do not touch them until the convulsions stop
4. Open the window to ventilate, change 1/3 to half the water with dechlorinated water at the same temperature, add activated carbon and increase aeration

AnswerD. Open the window to ventilate, change 1/3 to half the water with dechlorinated water at the same temperature, add activated carbon and increase aeration

ExplanationInsecticide ingredients such as pyrethroids are highly toxic to fish; once they dissolve in from the surface they cause convulsions and breathing difficulty. The correct response is to open the window immediately to ventilate, change 1/3 to half the water with dechlorinated water at the same temperature to dilute the chemical, adsorb it with activated carbon, and increase aeration. The label claim that it is safe for people and pets refers to mammals and does not apply to fish. Moving them to a bucket does not reduce what is already in their bodies and delays the work of diluting the tank water. Turning off the lights does nothing to stop the poisoning. Continue water changes the next day; for fish that keep convulsing or lie on their sides, consult a specialist shop or fish vet the same day.

IssuesThe owner did not know insecticide is harmful to fish and sprayed with the lid open in the room with the tank. The rules for using chemicals in the tank room had not been shared with the family.

ImprovementNever use insecticide, air freshener or deodorizing sprays in the room with the tank; if unavoidable, move the tank to another room or seal it with the lid and a bag, and stop the air pump. Tell the family that chemicals are banned near the tank and post a label.

A March morning. Fine bubbles linger on the tank surface without popping, and the four pond loaches have slimy, whitish skin with mucus drifting in threads. For yesterday's water change, a bucket freshly washed with dish detergent was used after only a light rinse. The fish are sluggish on the bottom and intestinal breathing has increased.

What is the most appropriate first action?

1. Skim off the bubbles with a net and it will be fine
2. Do a full water change and wash the substrate again with detergent
3. Prepare dechlorinated water at the same temperature in a detergent-free container, change 1/3 to half the water, add activated carbon, and keep changing water the next day
4. Add extra salt to neutralize the detergent

AnswerC. Prepare dechlorinated water at the same temperature in a detergent-free container, change 1/3 to half the water, add activated carbon, and keep changing water the next day

ExplanationPersistent bubbles and excess mucus are symptoms of surfactant from detergent left in the bucket irritating the fish's membranes. The correct response is to prepare dechlorinated water at the same temperature in a detergent-free container, change 1/3 to half the water to dilute it, adsorb it with activated carbon, and continue water changes from the next day on. Skimming bubbles leaves the chemical in the water. A full change pushes weakened fish over the edge with abrupt change, and washing the substrate with detergent creates a new source of contamination. Salt does not neutralize detergent. Loaches partly breathe through mucus and skin, so surfactants affect them especially strongly. Increase aeration and rest sluggish fish; if any lie on their sides, consult a specialist shop or fish vet the same day.

IssuesTank equipment and household equipment were not kept separate, and a detergent-washed bucket was reused for the tank. The owner did not appreciate that even a trace of detergent is fatal to fish.

ImprovementDedicate buckets, hoses, nets and sponges to the tank, label them, and never use detergent on them. Clean tank equipment with tank water or tap water only. Share the rule with the family that no detergent is used on tank tools.

June. Eight pond loaches were put into a 60 cm tank set up 2 weeks ago and fed generously every day. This morning the water is cloudy white and smells fishy; two fish are lying on the bottom and the rest are near the surface breathing through their intestines repeatedly. No water change has been done yet. A test kit shows high nitrite.

What is the most appropriate first action?

1. Change half the water with dechlorinated water at the same temperature, stop feeding, and for the next several days do a daily 1/3 change and test the water
2. Add triple the label dose of bacterial starter to cycle the filter at once
3. Remove only the two fish lying down and leave the rest as they are
4. Switch to a more nutritious food to build their strength

AnswerA. Change half the water with dechlorinated water at the same temperature, stop feeding, and for the next several days do a daily 1/3 change and test the water

ExplanationRight after setup the filter bacteria are immature, and too much food and too many fish send ammonia and nitrite soaring, poisoning the fish. Lying flat and frequent intestinal breathing are the symptoms. The correct response is to change half the water with dechlorinated water at the same temperature to lower the concentration, stop feeding to cut off the source of waste, and for several days do a daily 1/3 change and test the water. A large dose of bacterial starter does not reduce toxins immediately and can even worsen water quality. Removing only the fish that are lying down leaves the rest to be poisoned in the same water. Food is the source of the toxins; more makes it worse. For fish that keep lying on their sides, consult a specialist shop or fish vet the same day.

IssuesThe owner did not wait for the filter to cycle, added eight fish at once, and overfed. They had a test kit but did not use it until symptoms appeared.

ImprovementRun a new tank for 2–4 weeks, start with 2–3 fish and add more gradually. During startup, feed a small amount every other day and test nitrite every 3 days. Treat cloudiness or a fishy smell as a danger signal and change water at once.

August. Sinking food opened more than six months ago and starting to clump from humidity has been fed continuously. For the past few days, three pond loaches take food into their mouths and spit it out, and one has a swollen belly with white, stringy feces trailing. Water is 27°C and water quality is good. The food bag sits beside the tank in direct sunlight.

What is the most appropriate response?

1. Feed a little more so that more fish eat
2. Spitting it out is a matter of taste, so just switch to another brand
3. Switch to floating food to avoid leftovers
4. Discard the old food, fast them for 2–3 days to rest the gut, then restart with fresh food in small amounts

AnswerD. Discard the old food, fast them for 2–3 days to rest the gut, then restart with fresh food in small amounts

ExplanationFood stored in heat and humidity after opening oxidizes and grows mold, and fish that eat it develop indigestion or enteritis. Spitting out food, bloating and white stringy feces are the classic signs. The correct response is to discard the old food, fast them for 2–3 days to rest the gut, then restart with fresh food in small amounts. Feeding more adds to the gut's burden. Just switching brands does not let a gut weakened by spoiled food recover. Loaches forage on the bottom; floating food is hard for them to eat and is left to foul the water. If bloating does not improve after fasting, or red spots or raised scales appear, Aeromonas is possible, so consult a specialist shop or fish vet the same day.

IssuesFood was stored in a hot spot in direct sunlight. The owner did not realize opened food has a shelf life and did not notice that clumping food was abnormal.

ImprovementBuy food in small bags, store opened food in a sealed container in a cool, dark place, and use it up within 2–3 months. Write the opening date on the bag. Check the smell and texture before feeding and discard anything off. Add feces to the daily observation list.

A scorching August day. The owner went out with the air conditioning off, and on returning in the evening the tank in the room with afternoon sun reads 33°C. Five pond loaches are limp near the surface with frequent intestinal breathing, and one is starting to lie on its side. The water is slightly cloudy white. There is no cooling fan.

What is the most appropriate first action?

1. Drop ice straight into the tank to bring it down to 20°C at once
2. Turn on the air conditioning, increase aeration, and lower the temperature 1–2°C per hour by floating bagged ice packs and similar methods
3. Do a full water change with cold tap water
4. Move the fish to a bucket of water chilled in the refrigerator

AnswerB. Turn on the air conditioning, increase aeration, and lower the temperature 1–2°C per hour by floating bagged ice packs and similar methods

ExplanationAbove 30°C loaches weaken rapidly from oxygen deficiency and metabolic stress. The correct response is to lower the room temperature with the air conditioning first, increase aeration to supply oxygen, and bring the water down gradually at 1–2°C per hour by floating ice packs in bags and similar methods. Ice dropped straight in chills locally, and the temperature shock kills weakened fish. A full change with cold tap water is a double shock of chlorine and sudden temperature difference. Refrigerated water is equally dangerous as a sudden change. The target is 28°C or below, but take several hours and do not rush. Keep fish lying on their sides dark and quiet to recover; if still motionless the next morning, consult a specialist shop or fish vet the same day. Cloudiness signals deteriorating water quality, so do a 1/3 change at the same temperature the next day.

IssuesThe tank was placed where the afternoon sun hits, and the owner went out on a scorching day with the air conditioning off. They did not appreciate that summer heat is life-threatening for loaches and had no cooling fan or other preparation.

ImprovementPlace the tank out of direct sunlight and afternoon sun, and keep a cooling fan and aeration running in summer. Leave the air conditioning on at around 28°C even when out. Check the thermometer every morning and evening and keep ice packs in the freezer.

A September night. A typhoon has caused a power outage, stopping the filter and air pump on a 60 cm tank. Eight pond loaches are rising to the surface more often. Water is 26°C. There is no estimate for restoration, and the owner has no battery-powered air pump. The tank has substrate and a few plants.

What is the most appropriate response during the outage?

1. Loaches can breathe through their intestines, so nothing needs to be done
2. Place candles near the tank to keep the water warm
3. Open the lid slightly to increase the surface exposed to air, add oxygen manually by scooping water in a cup and pouring it back from above, and stop feeding
4. Standing water goes bad, so do a full change with tap water

AnswerC. Open the lid slightly to increase the surface exposed to air, add oxygen manually by scooping water in a cup and pouring it back from above, and stop feeding

ExplanationWhen the outage stops water flow and air supply, dissolved oxygen falls, and with eight fish it runs low within hours. Loaches can supplement with intestinal breathing, but that alone is not enough; the increased surfacing shows oxygen is already short. The correct response is to open the lid slightly to increase contact with the air, regularly scoop water in a cup and pour it back from above to agitate the surface, and stop feeding to reduce oxygen consumption and waste. When opening the lid, watch for jumping and keep the gap small. Candles are a fire hazard and do nothing. A full change with tap water weakens the fish with chlorine and abrupt change. In a prolonged outage, use a battery-powered air pump if one can be obtained.

IssuesNo battery-powered air pump had been prepared for outages. The owner kept many fish in one tank without considering the risk of the oxygen supply stopping.

ImprovementKeep a battery-powered air pump and spare batteries beside the tank as part of a disaster kit. Write out the outage procedure (adjust lid, pour water by hand, fast) and post it. Before a typhoon, do a water change in advance to give the water quality some margin.

Late on a February night, an earthquake of lower 5 intensity struck. About 1/3 of the tank water spilled on the floor, the lid slid open, and the heater is now exposed above the waterline. All three pond loaches are still in the tank, buried in the sand, but the spilled water has wet the area around the power outlet. Aftershocks are possible.

What is the most appropriate first action?

1. First unplug the heater to cut the power, put the lid back and secure it, wipe up the spilled water, then check on the fish
2. Top up with tap water right away to restore the water level
3. Move the fish to a bucket and evacuate them to a safe room
4. Touch nothing until the shaking settles and wait until morning

AnswerA. First unplug the heater to cut the power, put the lid back and secure it, wipe up the spilled water, then check on the fish

ExplanationA heater exposed above the waterline can run dry, break or start a fire, and a wet outlet risks electric shock, so cut the heater's power first. Next, put the lid back and secure it to prevent jumping during aftershocks, and wipe up the floor to reduce the risk of shock and slipping, then check on the fish. Topping up with plain tap water weakens the fish through chlorine and temperature difference; restore the level only after preparing dechlorinated water at the same temperature. Moving the fish to a bucket in the dark in the middle of the night invites jumping and falling accidents and adds needless stress during the shaking. Leaving it until morning risks the heater running dry or the tank toppling in an aftershock.

IssuesThe heater became exposed in the earthquake and the outlet was where it could get wet. The setup did not anticipate earthquakes: the stand was not anchored and the water level was not managed.

ImprovementAnchor the stand to the wall, keep the water level 5 cm or more below the rim and secure the lid. Mount the heater horizontally in a low position so it stays submerged even if the level drops. Place the outlet higher than the tank or well away, and keep a flashlight beside the tank.

October. Heavy rain has triggered an evacuation order, and the owner must head to the shelter within 2 hours. They keep four pond loaches and two golden loaches, and tanks cannot be brought into the shelter. On hand are plastic bags, a foam box, a battery-powered air pump, dechlorinator and plastic food containers. The outside temperature is 18°C.

What is the most appropriate response?

1. Load the whole tank into the car and leave it in the shelter parking lot
2. Put just the fish, with no water, in a plastic container and carry them
3. Release them in a nearby river to return them to nature
4. Divide them into bags with tank water and plenty of air, a few per bag, place in the foam box, and carry them with the battery-powered air pump supplying oxygen

AnswerD. Divide them into bags with tank water and plenty of air, a few per bag, place in the foam box, and carry them with the battery-powered air pump supplying oxygen

ExplanationThe safest way to take fish during an evacuation is to divide them 2–3 per bag with tank water and plenty of air, keep the bags dark and insulated in a foam box, and supply oxygen with a battery-powered air pump. Carrying the whole tank means water spilling and glass breaking in the car, a serious hazard during disaster travel. Carrying them without water kills them by drying, even with intestinal breathing. Release introduces pathogens and genes from captive fish into the wild, an act that destroys ecosystems; even with loaches it disrupts local populations and is prohibited. At the shelter, stop feeding for several days, limit temperature swings, and once settled change water gradually with dechlorinated water.

IssuesThe owner had not thought in advance about how to take the fish during an evacuation, so bagging, insulation and oxygen were improvised on the day. Even considering release shows a lack of awareness of the law and the ecosystem.

ImprovementStock the disaster kit with bags, rubber bands, a foam box, a battery-powered air pump and dechlorinator, and write out the evacuation procedure. Check in advance whether the shelter accepts animals and decide on a place that could take them. Resolve never to release them.

A January morning. Three pond loaches are kept in a water lily pot on the balcony, and a severe cold snap has frozen a 2 cm layer of ice on the surface. The water is 15 cm deep with mud and sand on the bottom. The water under the ice is still and no fish are visible. The daytime forecast is also below freezing, and the cold snap will last until tomorrow.

What is the most appropriate first action?

1. Break the ice with a hammer, find the fish and move them to warm water indoors
2. Pour boiling water on the ice to melt it
3. Cover the pot with foam board or cloth to slow the freezing, and if the whole volume may freeze, move the pot to a cold spot indoors
4. Loaches overwinter in mud, so do nothing until spring

AnswerC. Cover the pot with foam board or cloth to slow the freezing, and if the whole volume may freeze, move the pot to a cold spot indoors

ExplanationLoaches tolerate cold and overwinter buried in mud, but in a pot only 15 cm deep a prolonged cold snap can freeze the water solid and the fish with it. The correct response is to cover the pot with foam board or cloth to reduce heat loss, and if there is a risk of the whole volume freezing, move the pot indoors to a cold room, preventing freezing while avoiding sudden temperature changes. Breaking the ice and moving them to warm indoor water subjects dormant fish to a shock of tens of degrees. Boiling water kills fish with local heat and cracks the pot. Left alone, a shallow pot can freeze solid. Do not feed until spring, and if the water drops, top up with water at the same temperature on a day above freezing.

IssuesThe owner did not anticipate the risk of a shallow water lily pot freezing solid in a cold snap. Knowing that loaches overwinter well led to complacency about the limits of the environment.

ImprovementKeep outdoor fish in a container at least 30 cm deep and insulate it in winter with foam board or a cover. When a cold snap is forecast, move the pot out of the wind the day before. In winter, check the ice thickness and water movement weekly, and move the pot indoors to a cold spot if it may freeze solid.

November. The owner kept cleaning the tank and treating a sick loach bare-handed with a cut on one finger. Two weeks later, the cut on that finger is red, swollen and oozing pus, and has become a small lump that will not heal. No fever. They have not seen a doctor and are just covering it with a bandage.

What is the most appropriate response?

1. See a dermatologist or physician and tell the doctor you had contact with tank water and treated a sick fish
2. It has nothing to do with the fish's illness, so keep applying over-the-counter ointment
3. Wash it with tank water and change the bandage
4. The lump will heal on its own, so just stay away from the tank until it does

AnswerA. See a dermatologist or physician and tell the doctor you had contact with tank water and treated a sick fish

ExplanationTank water and fish skin carry bacteria such as atypical mycobacteria and Aeromonas that infect people through wounds. A wound that becomes red, swollen and lumpy and will not heal is the classic course of atypical mycobacteriosis, also called fish tank granuloma, which requires diagnosis and treatment at a medical facility. The correct response is to see a doctor and be sure to mention the contact with tank water and the treatment of a sick fish. It does not heal with ordinary wound care, and that information is essential for diagnosis. Over-the-counter ointment is ineffective, and left alone the lump spreads. Washing with tank water puts the source of infection into the wound. Waiting for it to heal on its own is a mistake; see a doctor promptly for any wound lasting several weeks or more.

IssuesThe owner handled the tank with a cut on the hand and even treated a sick fish bare-handed. There was no awareness that tank water carries bacteria that infect people, and no habit of protecting wounds.

ImprovementWith a cut on your hand, skip tank work or wear waterproof gloves. Always wear gloves when handling sick fish and wash hands with soap afterward. If a wound or swelling after tank work does not heal, see a doctor promptly and be sure to mention the tank contact.

During the May holidays at the family home in the countryside. Pond loaches collected locally have multiplied, and the grandfather, saying people used to eat them alive, is urging his elementary-school grandchild to try live "dancing" loach. The fish were kept in an outdoor pond and it is unknown whether they carry parasites. The child is interested, and the grandfather already has vinegar soy sauce ready.

What is the most appropriate response?

1. It is a traditional way of eating them, so there is no problem
2. A good wash removes parasites, so wash them and let the child eat
3. Raw loach causes gnathostomiasis, so do not serve it raw; if eaten at all, only thoroughly cooked
4. It is dangerous for children, so only the adults eat it raw

AnswerC. Raw loach causes gnathostomiasis, so do not serve it raw; if eaten at all, only thoroughly cooked

ExplanationLoaches can carry Gnathostoma larvae, and cases of human infection from eating them alive have been reported in Japan. The larvae migrate under the skin causing swelling and pain, and rarely enter the eyes or nervous system. The correct response is not to serve them raw, and if they are eaten at all, only thoroughly cooked. The larvae are inside the fish and are not removed by washing. Being a traditional way of eating does not change the infection risk. Adults face the same danger as children. Eating pet fish is not advisable anyway, since their environment and feeding history are unknown. If someone has eaten it raw and develops migrating swelling under the skin, see a doctor and mention the raw fish.

IssuesThe family did not know raw loach carries a parasite risk and assumed it was safe because it was traditional. No one had looked into parasites in collected or outdoor-kept fish.

ImprovementAgree as a family never to eat pet or collected fish raw. Teach children that animals are for observing, and if eaten at all, only as cooked products from a professional supplier. Pass parasite knowledge on to the older members of the family too.

April. The net and pipette used in a loach tank under treatment for ich were also used, as is, in the neighboring tank of healthy striped loaches. Three days later, two striped loaches in the healthy tank are starting to show white spots. Equipment is shared, and the owner touches both tanks without washing hands.

What is the most appropriate response?

1. Move the striped loaches from the healthy tank into the tank under treatment and treat them together
2. Soak the equipment in bleach and immediately keep using it in both tanks
3. Discard all the fish in one tank and reset it
4. Separate equipment per tank, wash hands before touching, and treat both tanks by gradually raising the temperature and doing a 1/3 water change

AnswerD. Separate equipment per tank, wash hands before touching, and treat both tanks by gradually raising the temperature and doing a 1/3 water change

ExplanationThe ich parasite is easily carried to another tank by nets, pipettes and wet hands. The correct response is to first separate the equipment per tank, wash hands before and after touching, and treat both tanks by raising the temperature 1–2°C per day and doing a 1/3 water change. Moving fish into the tank under treatment puts them in an environment dense with pathogens, and the difference in water quality between tanks also causes shock. Bleach residue is highly toxic to fish; drying and rinsing under running water are safer. Discarding the fish is out of the question; ich is a disease that recovers with proper treatment. If medicating, do it carefully in a separate container with the loach's drug sensitivity in mind, and consult a specialist shop or fish vet if there is no improvement.

IssuesThe basic hygiene rule of separate equipment per tank was not followed, and hands were not washed. There was little awareness that disease spreads via tools and hands.

ImprovementDedicate color-coded, labeled nets, pipettes and buckets to each tank. Work on the sick tank last, and wash hands with soap before and after. Rinse used equipment under running water and dry it completely before storing.

July. Along with a water change, the substrate and filter sponge were washed in the kitchen sink and left to dry next to the dish sponge in the same holder. Afterward, family members complained of diarrhea and stomach pain lasting several days. The loaches are healthy, hands were washed before cooking, but the sink was not disinfected.

What is the most appropriate response and prevention?

1. The loaches are healthy, so the tank is unrelated; look for the cause of food poisoning in food only
2. Stop washing the sand and give up keeping fish
3. Keep washing tank equipment where the dishes are washed and just be thorough about hand washing
4. Family members see a doctor and mention the tank equipment washed in the kitchen; from now on never wash tank equipment in the kitchen and store it separately from dishes

AnswerD. Family members see a doctor and mention the tank equipment washed in the kitchen; from now on never wash tank equipment in the kitchen and store it separately from dishes

ExplanationEven when the fish are healthy, tank water and substrate can harbor bacteria such as Salmonella and Aeromonas that cause gastroenteritis in people. Washing tank equipment in the kitchen and drying it next to the dish sponge transfers bacteria to cooking tools and dishes. The correct response is for the family to see a doctor and mention that tank equipment was washed in the kitchen, and from then on never wash tank equipment in the kitchen and keep its storage completely separate from dishes. The fish's health and the risk to people are separate matters; looking for the cause in food alone leads to recurrence. There is no need to give up the fish; separating hygiene prevents it. Hand washing alone does not prevent contamination via equipment. Disinfect the sink after use, and take special care in households with children or the elderly.

IssuesTank equipment was washed and dried in the same place as dishes. There was no awareness that tank water and sand carry bacteria that infect people, and kitchen and tank work were not kept separate.

ImprovementWash tank equipment somewhere other than the kitchen, such as the bathroom or balcony, and dry it in a dedicated spot. Wash hands with soap after work, and disinfect the sink if it was ever used. Enforce a family rule that tank tools never enter the kitchen.

A June morning. In a 45 cm tank, one pond loach is lying on its side on the bottom; the body is still but the gill covers open and close slowly. After last night's water change, the owner noticed the water temperature had dropped 3°C. The other three are swimming normally. Aeration is on low and the water is clear.

What is the most appropriate first action?

1. Moving gills mean recovery is possible: set aeration to maximum, support it with its mouth facing the flow, and keep it dark and quiet
2. It is dying, so remove and dispose of it for the sake of the other fish
3. Shake its body by hand to stimulate it and keep going until it swims
4. Raise the water temperature 5°C above the original at once to bring it out of shock

AnswerA. Moving gills mean recovery is possible: set aeration to maximum, support it with its mouth facing the flow, and keep it dark and quiet

ExplanationFish cannot be given chest compressions, but moving gill covers mean recovery is possible. The likely cause is temperature shock from the 3°C drop during the water change, so the correct response is to set aeration to maximum to supply oxygen, support the fish with its mouth facing a gentle flow so water passes over the gills, keep it dark and quiet, and not touch it until it starts moving. Since loaches also breathe through the intestine, lowering the water level so it can reach the surface easily also helps. Disposing of a fish whose gills are moving is far too hasty. Shaking strips mucus and worsens it through stress. Sudden heating is a further temperature shock and can be fatal; restore the temperature within 1–2°C per day. If it is still on its side after several hours or the gill movement is fading, consult a specialist shop or fish vet the same day.

IssuesThe water temperature was not matched during the water change, causing a sudden 3°C drop. The owner did not know that gill movement in a fish lying on its side indicates a chance of recovery and nearly gave up.

ImprovementMatch change water to the tank temperature and confirm with a thermometer before pouring. Remember that moving gills mean revival is possible, and post the steps, boost aeration, support in the flow, dark and quiet, on paper. Keep a quarantine container ready.

A December night. In an unheated tank at 9°C, one pond loach lies completely still on the sand, belly tilted slightly upward. Gill movement cannot be seen by eye. The skin looks normal, and a light touch with a finger seems to get no response. The other two are buried in the sand.

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

1. Net it, take it out into the air, and leave it a while to see if it moves
2. Bring a light close and watch the gill covers for several tens of seconds; scoop it in a container with water to check whether the body bends and the eyes respond
3. It is not moving, so judge it dead and throw it away
4. Place food by its nose and judge by whether it eats

AnswerB. Bring a light close and watch the gill covers for several tens of seconds; scoop it in a container with water to check whether the body bends and the eyes respond

ExplanationIn cold water a loach's metabolism drops so far that gill movement becomes extremely slow and it can look dead. The correct response is to shine a light and watch the gill covers for several tens of seconds, and scoop it in a container with water to check whether the body bends and the eyes move. A live fish has elasticity; a dead one stiffens or goes limp and its eyes cloud white. Taking it into the air burdens a living fish and dries its chilled body. Discarding it just because it is not moving means disposing of a living animal. In cold water it does not respond to food, so appetite cannot be used to judge. Once confirmed alive, move it to clean water at the same temperature, increase aeration, and keep it dark and quiet. A belly tilted upward may also indicate an internal problem; if it continues the next day, consult a specialist shop or fish vet.

IssuesThe owner did not understand loach physiology in cold water and nearly declared it dead just for not moving. They had no concrete procedure for checking life or death, and keeping the tank unheated at 9°C added further strain.

ImprovementLearn the three checks, gill cover movement, body elasticity and eye clouding, as the life-or-death procedure. In winter, move the tank to a warm room so it never drops below 5°C. Keep a light and a small clear container beside the tank for checking.

February. A pond loach with a large ulcer on its belly is to be taken to an animal hospital that treats fish, an hour's drive away. The outside temperature is 5°C. An appointment has been made by phone. On hand are plastic bags, a plastic food container, a foam box, hand warmers, a thermometer and a battery-powered air pump.

What is the most appropriate way to transport it?

1. Fill the plastic container to the top with water, close the lid, and put it on the passenger seat
2. Put only water in a bag, squeeze out the air, tie it, and keep it warm in a pocket
3. Load the whole tank into the car
4. Bag it with tank water and plenty of air, place in the foam box with hand warmers taped to the outside, and carry it dark and unshaken. Bring water data and photos too

AnswerD. Bag it with tank water and plenty of air, place in the foam box with hand warmers taped to the outside, and carry it dark and unshaken. Bring water data and photos too

ExplanationThe basic method for transporting fish is to bag them with tank water and plenty of air, insulate in a foam box, and carry them dark and unshaken. In winter, tape hand warmers to the outside of the box to prevent sudden temperature changes. Use the battery-powered air pump on longer trips. Bring information useful for diagnosis: water temperature, pH, last water change, food, tank mates and photos of the symptoms. A container filled to the top has no air and the fish suffocates, and the passenger seat exposes it to jolting and light. A bag with the air squeezed out suffocates it, and a pocket overheats the water locally. Carrying the whole tank means spilled water, broken glass and an accident in the car.

IssuesThe owner had not thought about how to transport a fish in advance; without knowing the basics of air and insulation, a dangerous method could easily have been chosen. The information to give the vet also needed preparing.

ImprovementResearch a fish vet in advance and note the contact details. Keep transport bags, rubber bands, a foam box, hand warmers or ice packs, and a battery-powered air pump together. Keep a notebook of water parameters and water-change dates and bring it to appointments.

1 a.m. in August. Woken by a noise, the owner looks at the tank: all five pond loaches are at the surface with mouths open, gulping air continuously and not returning to the bottom. The air pump has stopped; its tubing had come off. Water is 29°C. The fish vet is not open at night.

What is the most appropriate first action?

1. Do nothing and wait until the vet opens in the morning
2. Move them all together into a small bucket and watch until morning
3. Reconnect the tubing and set aeration to maximum, agitate the surface to add oxygen, check the lid for gaps, and stop feeding
4. Add a large amount of tap water to supply oxygen

AnswerC. Reconnect the tubing and set aeration to maximum, agitate the surface to add oxygen, check the lid for gaps, and stop feeding

ExplanationAll fish gasping at the surface and not returning to the bottom is severe oxygen deficiency, an emergency that kills the whole tank within hours if left. The cause is the stopped air pump, so the correct response is to reconnect the tubing, set aeration to maximum, agitate the surface to increase contact with the air, and stop feeding to reduce oxygen consumption. Oxygen-starved loaches get excited at the surface and jump easily, so check the lid for gaps too. Waiting until morning is fatal; there is no need for a vet, as this can be handled at home. Crowding them into a small bucket reduces water volume and worsens the oxygen shortage. Chlorine in tap water damages the gills and the temperature difference causes shock. If any fish is lying on its side the next morning, rest it in clean water at the same temperature and consult a specialist shop or fish vet.

IssuesThe owner did not notice the air pump tubing had come off, so oxygen supply stopped overnight. There was no habit of checking equipment as a precaution against oxygen deficiency in warm summer water.

ImprovementMake a habit of checking that the air pump is running and the tubing connected before bed. In summer, keep the water at or below 28°C and run two air stones so oxygen continues if one stops. Keep a battery-powered air pump as a backup.

An October night. While the driftwood was being moved, a pond loach's barbel got pinched and is bleeding from the base. Blood trails in threads from its mouth and it is trembling in a corner of the tank. The bleeding continues after 10 minutes, though the fish can swim. Water is 22°C and water quality is good.

What is the most appropriate first action?

1. Take the fish out of the water and press hard on the bleeding spot with a tissue
2. Apply human styptic or antiseptic to the bleeding spot
3. Blood fouls the water, so do a full change with tap water
4. Place it in a quarantine container of clean water at the same temperature with 0.3–0.5% salt, increase aeration, keep it dark and quiet, and watch the bleeding and wound until the next day

AnswerD. Place it in a quarantine container of clean water at the same temperature with 0.3–0.5% salt, increase aeration, keep it dark and quiet, and watch the bleeding and wound until the next day

ExplanationThe basic rule for bleeding in fish is that it stops naturally when the fish rests in clean water. The correct response is to place it in a quarantine container of clean water at the same temperature with 0.3–0.5% salt to protect the mucus, increase aeration, keep it dark and quiet, and watch the bleeding and the wound until the next day. Taking the fish out of the water and pressing strips mucus and skin and stops it breathing, doing more harm than the bleeding. Human styptics and antiseptics are harmful to fish membranes and contaminate the water. A full change with tap water weakens it with chlorine and abrupt change. Barbels regenerate in a clean environment. If bleeding continues the next day, white cotton or ulcers appear at the mouth, or it cannot eat, consult a specialist shop or fish vet the same day.

IssuesThe layout was moved while the fish was near the driftwood, and its barbel got pinched. The owner did not know that fish bleeding is managed by resting in water and risked applying methods meant for land animals.

ImprovementCheck where the fish are before moving the layout and temporarily move them to a container if needed. Keep a quarantine container, salt and an air pump ready. Remember that fish bleeding is stopped in water, and keep time out of water to a minimum.

A July evening. Back from a 6-hour outing, the owner finds a golden pond loach on the floor 1 m from the tank, its skin almost dry and dusty. Its eyes are not clouded, and when prodded, the tip of its tail moves slightly. The room is 30°C, and there was a gap at the corner of the tank lid.

What is the most appropriate first action?

1. Place it gently in a shallow container of tank water to wet its body, increase aeration, keep it dark and quiet; return it to the tank if movement returns, and if not, do not give up for several hours
2. It is almost dry and cannot be saved, so dispose of it
3. Rinse the dust off under the shower and drop it into the tank
4. Rub the dry body by hand to make it produce mucus, then return it to the tank

AnswerA. Place it gently in a shallow container of tank water to wet its body, increase aeration, keep it dark and quiet; return it to the tank if movement returns, and if not, do not give up for several hours

ExplanationLoaches also breathe through the skin and intestine, and if the tail moves it is alive even with the skin almost dry. The correct response is to place it gently in a shallow container of tank water to wet its body, increase aeration, keep it dark and quiet, and return it to the tank once movement returns. Shallow water makes it easy to reach the surface to breathe. Even if it does not move for several hours, do not give up; check the gills and body regularly. Disposing of a fish whose tail moves is far too hasty. Shower water damages the weakened membranes with chlorine and pressure, and dropping it in is a dangerous impact. Rubbing the dry body peels the skin. After recovery, watch the skin for a week for cotton or redness; if it cannot swim or the belly swells, consult a specialist shop or fish vet the same day. Seal the lid gap the same day to prevent recurrence.

IssuesThe owner went out for hours with a gap left at the corner of the lid. They were not prepared for the fact that golden loaches, with pale coloring and weak eyesight, startle easily, or for the risk of faster drying in summer heat.

ImprovementSeal every gap in the lid, weigh it down, and keep the water level 5 cm or more below the rim. Make a habit of checking the head count and the lid before going out. Remember that a fish that moves goes back into water even if dry, and keep a shallow container and air pump within easy reach.