You will never be able to guess what has officailly killed TWO of my bullheads now. Bullheads have been in a tank with Green Sun fish, Pike Cichlids, Oscars, Largemouth, Senegal Birchir, and a 12" Pleco. The freaking pleco killed them. The second one I do not understand, I put all my fish into a larger tank, and the pleco started messing with him. Just as the first one, he sucked the slime right off him. Without its protective slime the bullheads skin is exposed and very frail. So it got scratched just by rubbing on something, it probably got sick, and died. I no longer like pleco's.