I'm new to fish, recently my uncle died and I inherited his tropical tank. Its a tank that hes had for years and it has a full grown RTS. Personally from reading other threads I think its over crowded. But with him having this tank with these same fish for a number of years I'm not sure if its the case. But the RTS has a completely transparent tail and I want to know if its ill, I have been testing the water daily and all the levels are ok, maybe its the stress from the move? In the tank there are 4 catfish, 3 small plecos, 3 loaches and 1 molly and a handful of neons. The tank is 25l, I also understand this is too small, however as we didnt intend on being fish owners we have to make do with it until we can afford a bigger one. Is there anyway to make his tail red again?