Males construct nests in secluded areas around hollow logs and under cut banks, in depths of 3-15 feet. The yellow gelatinous egg mass is continuously agitated by fin movements of the male to provide oxygen and flush away silt. In addition, the presence of the male prevents predation. After the fry have hatched and begun swimming, they remain in a compact school near the nest for several days before dispersing. Like most catfish, the flathead catfish is a nocturnal feeder, with activity peaks around dusk and dawn.
Flathead catfish are an introduced species.
Its native range is includes the Ohio, Mississippi and Missouri River basins. Since its introduction into Santee Cooper Reservoir in 1965, the flathead has been spread to nearly all other coastal rivers, where it has decimated redbreast sunfish and bullhead populations. Because of it voracious appetite, it is considered to be a nuisance in all coastal steams. Their negative effect on sportfish is negligible in large impoundments. It is unwise and unlawful to move flatheads flathead catfish from one public water body to another.