Why did my black Moor goldfish suddenly lose its tail and fin?

Thanks for reaching out about your fish. Water quality or aggression by other fish should be considered. Testing water quality for pH, ammonia, nitrite and nitrate, correcting any problems. The fins should re-grow is the problem is corrected. Good luck.

This could be a bacterial or fungal infection. If there are other fish in the tank, trauma cannot be ruled out. if there are other fish, ideally Tiny should be removed to a quarantine or hospital tank for treatment. If not, you can treat Tiny in the main tank. First, confirm adequate water quality. You can use a home test kit or submit a water sample for testing. The local Petco may offer water testing for free or for a small fee. Aim for an absence (0ppm) of ammonia and nitrites with nitrates at 20ppm or less. perform partial water changes, no more than 30% total volume at a time, using conditioned and temperature matched water. Goldfish are cold water fish that do best between 68 and 74 F. The filter should be rated for at least twice the volume of the tank. Plain aquarium salt (NOT table salt) can be used to reduce stress, treat minor infection and aid in recovery. Dissolve 1 tablespoon of salt per 5 gallons in a cup or two of two of tank water and gently pour it in. Treat for 10-14 days then perform water changes to reduce salinity. Only treat the amount of water being replaced. More often than not, pristine water quality will allow recovery of minor infections or trauma. If necessary, you can use a broad spectrum antibiotic or all in one product, such as LifeGuard (Tetra) or All In One Remedy (Marineland), to treat the tank. You can find these products in the Aquarium section of the local Petco or online. Follow label directions carefully and remove the carbon filter insert during treatment.

Thanks for reaching out about M.S. First of all, check water quality for pH, ammonia, nitrites and nitrates, correct any problems. Poor water quality can lead to dermal changes/irritations that can results in tattered scales or fins, and other dermal lesions. If the lesions progress, a veterinary visit is needed to assess and provide a diagnostic/treatment plan. Any of the over-the-counter medications to add to the water, rarely improve conditions but will more likely be a detriment to water conditions. Good luck.

Hi, and thanks for your question. This is a quite concerning presentation and it is likely to be related to water quality. 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 good and there are no major imbalances, your fish should get examined to look for any sign of bacterial/fungal infection and eventually water should be treated. Hope this answer was helpful, but please do not hesitate to contact us again on the forum or by requesting a consultation if you have any more questions or to discuss it any further. If this answer was helpful please let us know, this will be used to improve our service!

Thank you for the picture - I am unable to tell if the tail is just turning transparent, or if portions of it are missing. If it is truly just a color change, and there are no other problems with C.G. or the other fish, it may just be that he is going to become a different color. If the tail has missing portions, that is more likely to be caused by an infectious problem (such as bacteria, fungi, parasites). I would recommend evaluating your water quality parameters, as you eluded to in your question. Then I would monitor the tail, and if there are portions missing, I would recommend having him evaluated by a veterinarian. They can take samples of the area, as well as from the skin and gills to evaluate for parasites and other organisms.

Elevated ammonia levels can result in "burns" which may turn fins and scales black. Use a home test kit or submit a water sample for testing. Most pet or fish stores will do this for free or for a nominal fee. If ammonia levels are elevated, daily partial water changes, using aged or conditioned water, can decrease ammonia to safe levels (0.25 ppm or less). StressCoat or plain aquarium salt (NOT table salt) can aid in healing. Dissolve 1 teaspoon of salt per gallon of water into a cup of tank water and gently pour it into the tank. Confirm adequate filtration. The filter should be rated for at least twice the volume of the tank. You can change 20-30% of the tank water every couple of weeks. Use only aged or conditioned water that is temperature matched to prevent stress or shock.

This presentation could be compatible with fin rot, which is a bacterial or fungal infection. It is unlikely that the primary cause is traumatic, unless Tank is itchy (that could be compatible with a bacterial infection anyway) and he is scratching himself constantly. The approach must be logic anyway starting from water quality check and treating with some antibiotics. Begin by submitting a water sample for quality testing. Most pet stores will do this for free or a nominal fee. If water quality is good and there are no major imbalances, water should be treated with antibiotics. Please do not hesitate to contact us again on the forum or by requesting a consultation if you have any more questions or to discuss it any further.