I have a 20 gallon tank with 2 channel cats, 2 crawdads, 1 bluegill, and 1 longear(I think). The biggest channel cat is about 5 3/4 inches. Like Bill said the tank is overcrowded. I would cut all of their numbers in half, at least. You should put a few crawdads in there, they are interesting to watch. Make sure that they cant get out. I have had one escape twice.
