Catfish (Tandanus tandanus) are scavengers, generally bottom feeders, but will eat small fish that will fit in their mouth. Temperature tolerance is wide. Anything your other fish can handle, they will be happy with. The big bonus is, they are top eating. Their flesh is white and delicate. When you are ready to eat them just humanely dispatch them. Before gutting and heading them, pour hot water over the skin. Then the skin can easily be peeled off. The protective coating of mucus will not be slippery once the hot water has been applied. Cook them a bit longer than perch to produce the best texture. Undercooked, they can be a bit too moist.
Another big bonus... they will breed in dams.