This fish is rarely mottled in color. The black bullhead spawns in May or early June, usually in weedy or muddy shallow areas. Saucer-shaped nests are constructed in the mud or sand in about 2 to 4 feet of water. These nests range from about 6 to 14 inches in diameter and up to l0 inches deep. The number of eggs deposited depends on the age and size of the female, but the average is about 2,000 to 6,000, or more.
Incubation is completed in a week or less under normal conditions.
The young fry stay in tight black, ball-like schools until they reach nearly 2 inches in length, at which time they leave their parents to shift for themselves. The black bullhead is usually the smallest-sized bullhead, but in larger lakes of northern Iowa some reach a weight of two pounds or more. The record fish in Iowa came from a farm pond in Harrison County and weighed 4 pounds, l2 ounces. In streams or lakes where food is scarce and the population density is quite high, they are much smaller and seldom exceed 7 to 9 inches. The black bullhead is strictly omnivorous, feeding upon nearly every conceivable thing in the water.