calico fantail

Question
I have a 10 gallon tank with 7 small variations of goldfish and fantails, all of my fish seem to be doing fine, except one fantail, that does nothing really but sit on the bottom of the tank. The fish will swim up to eat and seems very healthy. The fish has small red blotches on its underside that I do not remember being there before he started sitting on the bottom. I've changed water, filters, taken out some of the live plants, cleaned the filter itself, but nothing seems to make my fish swim around like normal. What can I do to help my fishy??

Answer
Hello Mary -

In all honesty, your tank is much too small for 7 goldfish, even if they are only 1 inch long. Goldfish produce so much more ammonia than other fish that they can quickly overwhelm a 10 gallon filter. Some fish are more tolerant to ammonia, while others decline quickly. Also, if you are keeping "Y-tailed" fish (i.e. fantails) with "V-tailed" fish (i.e. comets, shubinkins) then you are likely experiencing some amount of bullying. The fantail you're seeing is probably at the bottom of the pack and is incredibly stressed from being bullied. The stress will make him more susceptible to ammonia poisoning. Red blotches are a common sign of ammonia poisoning, especially near the gills.

If you want to help the fantail, and all of your other fish, I would split the group up. Keep all "V-tailed" fish in one tank, and get another tank for your "Y-tailed" fish. Or, you can get one large tank and move the entire group into that new tank. I know it can be expensive, but there is no way all 7 fish will be able to live in a 10 gallon tank, especially once they start growing. Once they are full grown, they can be 4 or 5 inches long each, which would give you around 30 inches of fish in a 10 gallon aquarium.

Hope this helps, and sorry if it isn't what you wanted to hear.
-Amber Worman