Experiments conducted from 1938 to 1941 indicated that large flathead catfish were predatory and in several cases eliminated the larger bluegiIls. In the 1962 experiments, 2- to 5-inch flatheads eliminated almost all the fathead minnows, while the larger flatheads (10") stocked in 1963 experiments apparently fed on larger bluegills in preference to fatheads. They eliminated all the large bluegills they could swallow except for a few in the 7-inch group and had left very few in the 4- to 6-inch groups. This apparently indicated a preference for larger fish as the flatheads increased in size, and suggests that the large flathead may compete with fishermen for fish of harvestable size. These experiments indicate that flathead catfish of all sizes should be listed as a "c" (piscivorous) species in population analysis. The smallest fish would eat any other small enough to be swallowed. Where they could not swallow another of their OW11 species, they oftsn severly wounded them by biting.
