can you give some info on the tank? temp,water parameters,feeding schedule,tank size,activity level,what is your source water, other occupants and age of the fish in question. does this fish seem lopsided at all? is the actual anal vent protruding,or is it the tissue around the vent?has the tank temp gone down due to winter?i looked at your info and it did not say where you live.sorry about all of the questions,but i need info in order to assist you.