Brown bullhead are monogamous during the breeding season. Blumer (1985) and Becker (1983) were unable to determine how pairing occurred. Courtship, occurring near nesting sites, involves holding the partners jaw, tail, or head with the mouth, head butting, nibbling bodies, and caressing barbels. Side-by-side swaying has also been observed. Pairs settle over nests and face away from each other during gamete release.
Mating System: monogamous
Brown bullhead spawn once during the spring and early summer breeding season. During an extensive four year study in Michigan by Blumer (1985), this species spawned most frequently within the first 16 days of June. He also found that larger males spawned earlier in the season. In New Zealand, these fish spawn between September and December. They reach sexual maturity at 3 years of age. Nests, typically built by females but sometimes by pairs, are excavations made in the sand, gravel, mud, under roots, and within the shelter of logs and vegetation in shallow water. Substrate is sucked into the mouth and relocated during nest building. Sheltered nests are thought to provide protection from predators. Eycleshymer (1901) noted nests in pieces of stovepipe and a bucket. During nest construction males are territorial. Egg clusters contain 50 to 10,000 eggs. Brown bullhead demonstrate iteroparity. Fertilization is external.
Breeding interval: Brown bullhead spawn once during a breeding season.
Breeding season: The breeding season is during the spring and early summer.
Range number of offspring: 50 to 10,000.
Range time to hatching: 13 (high) days.
Average time to hatching: 5.6 days.
Average time to independence: 9.4 days.
Average age at sexual or reproductive maturity (female): 3 years.
Average age at sexual or reproductive maturity (male): 3 years.
Key Reproductive Features: iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; fertilization (External ); oviparous
Demersal eggs are incubated and guarded by one or both parents who fan the eggs with their fins, which may minimize fungal infection and help with development. After hatching, larvae on the nest and schooling juveniles are guarded by one or both parents who chase away other fish. If juveniles leave the school, parents will capture them and return them with their mouths. Blumer (1985 and 1986a) found males to be primary caregivers: 56.2% of broods were cared for by both sexes, 39.3% by males only, and 4.5% by females only. Maximum length of parental care is 29 days.
Parental Investment: male parental care ; female parental care ; pre-fertilization (Provisioning, Protecting: Female); pre-hatching/birth (Provisioning: Female, Protecting: Male, Female); pre-weaning/fledging (Protecting: Male, Female); pre-independence (Protecting: Male, Female)