I have had many different "experiments" with what fish to put in with him, most didn't work. Ikeep him alone right now. He does eat anything he can as soon as he grows large enough. I plan to get some sunfish or perch to put in with him, but since they are wild fish I want to wait until after spawning season to grab some fresh ones that aren't too accustomed to the wild life. And the record bullhead size in connecticut is 4 pounds 15 ounces.