Why did my fish die with a bloody eye and wound? How to prevent it?

It could be an infection (bacterial or fungal) or it could be due to trauma from other fish or tank furniture. Confirm proper water quality and chemistry. You can try some plain aquarium salt (NOT table salt or epsom salt) as a general tonic. It may reduce stress, improve gill function, treat minor infection and aid in recovery. Dissolve 1 tablespoon of salt per 5 gallons of water in a cup or two of tank water and gently pour it into the tank. Treat for 10-14 days then reassess the condition. Perform partial water changes to decrease salinity afterwards. Use only aged or conditioned water that is temperature matched to prevent stress or shock. Goldfish are cold water fish and do best between 65 F and 72 F.

Maintain pristine water quality and stable chemistry. If the fish is not a scaleless fish, you can use plain aquarium salt as a general tonic. It will reduce stress, increase gill function, treat minor infection and aid in recovery. Dissolve 1 tablespoon of plain aquarium salt (NOT table or Epsom salt) per 5 gallons of water in a cup or two of tank water and gently pour it into the tank. Treat for 10-14 days then reassess the condition of the injured fish. Partial water changes can be performed afterwards to reduce salinity. Use only aged or conditioned water that is temperature matched to prevent stress or shock.

I am so sorry that this is happening, and I am sorry for the loss of two of your fish. With you mentioning the filter stopping, there could be a number of issues going on. Filters perform a number of tasks, depending on the type you have. First, they help to keep toxins (ammonia, nitrites, nitrates) from building up in the water through the support of good bacteria - when the power goes out, sometimes the bacteria can die. This can put a lot of stress on the fish. Also, the oxygen levels can decrease when the power goes out (not sure if this occurred for you or not) and this can cause fish to die, and others to get stressed. When stress occurs, sometimes fish will injure themselves if they are panicked and trying to move around the tank. From the pictures, it looks like the reddened spots are under the skin and could be related to trauma. There are other issues that can result in spots that look like this as well. I would recommend getting your filter started back up, doing a water change, and then testing your water quality. Once it is back to normal, you can put your fish back in the tank. If your filter didn't stop due to a power outage, I would recommend considering replacing it, or attempting to find the underlying problem that resulted in its malfunction in the first place. For the reddened spots on the head - if they are due to trauma, they should resolve over the next week or so. If you see progression, or if there is a lack of improvement, then I would recommend taking one of the fish in for evaluation by a veterinarian, as there may be something else going on. I hope that this gives you a place to start, and good luck!

Thanks for reaching out. Not sure how when the lights were turned on, the fish responded when it had no eyes. Could the corneas be cloudy? This could be due to trauma from an aggressive fish, parasitic infestations, or infections. A veterinary visit would be recommended. If the one has no eyes, it needs to be humanly euthanized as can not find food and will starve to death or succumb to infection. Continue to test water quality and correct any problems. Good luck.

I'm sorry you are having difficulties with your aquarium. There are several issues that should be dealt with right now. They are water chemistry, aquarium size and choice/number of fish. Any new aquarium should be set up and, ideally, run empty for several weeks (usually 4-6 weeks). This is so beneficial bacteria have an opportunity to populate the substrate and filter. These bacteria are necessary to break down wastes that fish will produce. The technical phrase for this is "establishing the Nitrogen cycle". These bacteria will break down wastes into ammonia then nitrites then nitrates. Nitrates can then dissipate or be absorbed/used by live plants. In high enough concentrations, ammonia and nitrites are toxic and can kill fish. Cycling a tank with fish is possible but it increases the risk of loss. Water chemistry should be checked every few days using a liquid home test kit. A water sample can be submitted for testing , but is not as convenient as testing yourself. Most pet stores or fish stores will do this for free or for a small fee. Partial water changes, no more than 30%, can be done as needed to stabilize chemistry and maintain water quality. Choices for water conditioners include NovAqua, AmQuel Plus, Prime, StressZyme or StressCoat. Tank size is another concern. With most fish, the widely accepted "one inch of fish per gallon" will be sufficient. For koi and other carp species, including goldfish, the rule is not sufficient. At full size, goldfish need 20 gallons per fish with an additional 10 gallons for each additional fish. Koi do best in larger tanks, much larger...we're talking in the hundreds of gallons or small ponds. These species produce a larger than average bio-load (wastes) that can quickly affect water quality in a tank. To combat this, large water volumes and powerful filtration are required. Any filter should be rated for at least twice the tank volume. I'm not sure what size tank you have now, it may be fine if the fish are young and small, but they will quickly outgrow it. The last issue is choice of fish. Koi and goldfish are cold water fish. They do best in water between 65F and 72F. Most species of sharks do best in the high 70sF to low 80sF. Keeping fish in incorrect water temperatures will lead to stress and illness. This could be compounded by the water quality/chemistry issues you are having currently. Until the chemistry is stable and water quality is maintained, your fish will continue to become ill and possibly die. Any treatment will not be successful in this situation. Do not purchase or add any more fish until the tank has cycled. If you have additional questions, you can post them in the forum or request a consultation to discuss the case in greater depth.

I am sorry for your loss. Without an exam, it can be difficult to determine the cause of death. Possibilities include constipation, severe swim bladder disease, dropsy (kidney failure), other infection or trauma. If you have other fish in the tank, monitor them for similar symptoms. You should also test the water using a home test kit or by submitting a water sample for testing. The local Petco may do this for free or for a small fee.

It may be a bacterial infection or trauma. Monitor for bullying since you have other fish. Most minor infections can be managed or resolved by maintaining pristine water quality. A bit of plain aquarium salt (NOT table or Epsom salt) can be used as a general tonic to aid in recovery, reduce stress and improve gill function. Dissolve 1 tablespoon per 5 gallons of water in a cup or two of tank water and gently pour it into the tank. Treat for 10-14 days then reassess the condition. If the condition is unchanged, consider a broad spectrum antibiotic. You can find one in the aquarium section of the local Petco. Follow label directions carefully and remove the carbon filter insert during treatment if indicated.