Black Bullhead

Like most of the bullheads and flathead catfish, the black bullhead has a squared tail fin, in contrast to the forked tail of channel and blue catfish. It is a bottom-rover fish, meaning it is well-adapted for bottom living. It is typically dorsoventrally flattened, and has a slightly humped back. Its color depends on the area where it is taken, but it generally is darker than brown or yellow bullheads (A. nebulosus and A. natalis, respectively). It can be distinguished from the flathead catfish (Pylodictis olivaris) by the fact that the black bullhead's lower lip does not protrude past the upper lip. Distinguishing it from the brown bullhead is a bit more difficult, depending on the area where it is caught, but a distinguishing detail between the two includes weak serration on the pectoral spine of the black bullhead, while the brown's corresponding spine is more strongly barbed.

Black bullheads are native to the Mississippi and Ohio river basins and are widespread throughout the central and southern United States. They are largely absent from the Atlantic coastal drainages of the eastern US. They typically inhabit stagnant or slow-moving waters with soft bottoms, such as lakes, ponds, oxbows, and low-gradient streams. They have been known to congregate in confined spaces, such as lake outlets or under dams.

They are very tolerant fish, and are able to live in muddy water, with warmer temperatures and in water with lower levels of oxygen, which reduce competition from other fish. They are consistently more tolerant of high water silting, water pollution, and warm water temperatures than other bullhead species.

Black bullheads are omnivorous, so they eat almost anything, from grains and other plant matter to insects, dead or living fish, and crustaceans. Midge larvae and other young insects are the primary diet for adult bullheads. Black bullheads have been known to eat small fish and fish eggs as well. They have short, pointed, conical teeth, formed in multiple rows called cardiform teeth. Black bullheads have no scales; instead, they have about 100,000 taste receptors placed all over their bodies. Many of these are located on the barbels near their mouths. The receptors help the fish to identify food in their dark habitats. During the winter, black bullheads decrease food intake, and may stop eating altogether. Instead, they bury themselves around the shore line of the lake in debris, with only their gills exposed.

Black bullhead are gregarious fish and typically forage and move in schools. They remain inactive within beds of vegetation by day, and forage mainly at night.

Black bullheads start to spawn in April and continue through June. In Wisconsin and similar latitudes, spawning has been recorded as late as early August.

During mating, the females scoop out a small hole or depression in mud or sand, typically at a depth between 0.6–1.2 metres (2.0–3.9 ft) under the surface and beneath shelter such as vegetation, woody debris, or overhanging banks. They may also be made within muskrat burrows. Eggs are laid in a gelatinous mass and guarded by both parents, which periodically fan and stir the spawn with their tails and fins. Incubation time is dependent on the water temperature, and typically takes place over five to ten days.