Sorry this is kind of a double post, but I'm new and didn't realize this section was here. Anyway, we have a very small(about half an inch) convict in a 30 gallon tank all alone. It has been alone since it entered the tank. About three days ago it began to hide which is very unlike this fish. It has been eating, but less than normal. Today we noticed it's left side fin was being held right up against it's body and it was not using it to swim. It normally swims rather smoothly unless fighting the current, however beginning today it is darting around very strangely. Any help on what this is or how to treat this would be great. By the way ammonia, nitrates, and nitrites are all reading zero, ph is 7.9,and temp is 80.