Large flatheads are the apex predators of their waters, and will eat anything smaller than large gar, large stripers, or large Blue catfish. Largemouth bass do not typically get big enough to avoid being consumed by large flatheads, but IMO the carp, bullheads, gizzard shad, and crappie would be easier prey. In their native waters, flatheads do not decimate other species. They are native to our small local river (white river), but there are still plenty of sunfish, bass, and channel cats to catch.