Right now I got two bullheads in a 120 gallon native community with different species of sunfish and a couple of perch. Ones a black and the other is a brown, there both between 9-10 inches, they are very interesting fish with a lot of personality, there always on the move, but they never bother any of the other fish. The only real problem with bullheads that I've had is that they grow surprisingly fast and they are bottemless pits when it comes to food.