Why did my new aquarium fish suddenly lose its eyes overnight?

This could be caused an extreme exophthalmus that has rupture both eyes and could be secondary to an infection. Gas bubble disease can lead to eyes rupture as well. Eyes unfortunately do not regenerate but can heal depending on the type of injury (a picture of the lesions would be extremely helpful in your case). Begin by submitting a water sample for quality testing. Most pet stores will do this for free or a nominal fee. Clinical examination should always include a water quality check, even if you have done so already. Water testing should be performed with a quality test kit, measuring NH4, NO2 and NO3. High ammonia levels, PH imbalances may be responsible for these signs. Oxygen concentration and quality of the filters should be determined as well. If water quality is normal, antibiotic treatment is likely to be required. Please discuss these options with your local vet.

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.

Infection, old age, poor water quality or poor nutrition are all possible causes. The "wound" may have been post mortem, caused by being eaten by tankmates. Monitor tankmates for signs of illness or infection (red spots, fuzzy spots, swelling, lack of appetite/activity, etc.). Submit a water sample for quality testing or use a home kit to test for chemical imbalances. You may need to perform water changes, treat with chemicals or treat with antibiotics or antifungals depending on symptoms. You can request a consultation to discuss the situation in more detail.

Thanks for reaching out about Morty. Ich treatment need to be perfumed for several weeks at least. If mostly gone, means to continue treatments. Check water quality because high ammonia or nitrates can lead to corneal edema. A visit to a veterinarian might help with the diagnosis. Good luck.

This may be a severe infection. If you haven't already, move him to a separate hospital tank. Maintain pristine water quality via filtration and regular water changes. Use only conditioned water that is temperature matched to prevent further stress or shock. Consider a broad spectrum antibiotic. Look for KanaPlex or Maracyn Plus in the aquarium section of the local Petco. Follow label directions carefully and remove the carbon filter insert during treatment. Unfortunately, given the severity of the condition and his appearance, it is possible you may lose him during treatment.

Thanks for reaching out about your fish and including photos. Don't think it ruptured as these usually collapse. Corneal bleeding can be due to trauma or ruptured blood vessels from disease. Check and correct water quality. A veterinary visit is recommended to assess and establish a diagnostic/treatment plan. Good luck.

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.