Ameiurus nebulosusBrown catfish(Also: Bullhead; Catfish; Common bullhead; Common catfish)

Geographic Range

Brown bullhead are native to freshwater habitats in Canada and the United States from 25° to 54° north latitude. They are distributed in the Atlantic and Gulf Slope drainages, ranging from Nova Scotia and New Brunswick to Mobile Bay, Alabama, and in the Great Lakes, Hudson Bay, and Mississippi basins from Quebec west to southeast Saskatchewan and south to Louisiana. Brown bullhead have been introduced outside of this range, including countries of northern, western, and eastern Europe, the Middle East, New Zealand, Chile, and Puerto Rico (U.S.). They have also been introduced and well established in the western United States and British Columbia. (American Fisheries Society, 2004; Barnes and Hicks, 2003; Fisheries and Oceans Canada, 2010; Froese and Pauly, 2010; Page and Burr, 1991)


Brown bullhead are found in pools and slower-moving runs of creeks and rivers, reservoirs, ponds, and lakes. They are tolerant of a wide range of environmental conditions, including water temperatures up to 36 degrees Celsius and oxygen levels to 0.2 ppm. They prefer habitats with vegetation and substrate. They survive well in domestically and industrially polluted waters. They are bottom dwelling fish. (Barnes and Hicks, 2003; Becker, 1983; Blazer, et al., 2009a; Blazer, et al., 2009b; Fisheries and Oceans Canada, 2010; Froese and Pauly, 2010; Page and Burr, 1991)

Physical Description

Brown bullhead look very similar to black bullhead (Ameiurus melas) and yellow bullhead (Ameiurus natalis). Brown bullhead are distinguished by 5 to 8 large, serrated teeth on their pectoral spines , mottled coloring on their trunk, lack of dark fin rays, and 11 to 15 gill rakers on their first gill arch. An occasional solid colored trunk has been described. They have 8 dark brown to black barbels on their head (two nasal, two maxillary, and four on the chin) which are sensitive to touch and chemical stimuli. The anterior portion of their body is thicker than the posterior portion. The body is scaleless with a brown to black dorsal side and a lighter ventral side. In captivity, this species loses pigmentation, becoming whitish. They have terminal mouths with a slightly longer upper jaw and a mouth filled with irregular rows of tiny teeth on both jaws. However, Baily et al. (2004) described their jaws as being equal. Their head is dorso-ventrally flattened. They have one dorsal fin, an adipose fin, and a caudal fin with a slightly indented fork. Typical adult length is 200 to 300 mm but they may reach up to 500 mm. Adults typically weigh 0.5 kg, but have been recorded at 3.6 kg. No significant difference has been found between male and female size. (Baily, et al., 2004; Barnes and Hicks, 2003; Becker, 1983; Blumer, 1985; Michigan Department of Natural Resources and Environment, 2010; Nelson, 1984; Page and Burr, 1991; Rasquin, 1949; University of Wisconsin Center for Limnology, et al., 2010)

  • Sexual Dimorphism
  • sexes alike
  • Range mass
    3.6 (high) kg
    7.93 (high) lb
  • Average mass
    0.5 kg
    1.10 lb
  • Range length
    500 (high) mm
    19.69 (high) in
  • Average length
    200-300 mm


Mean daily water temperature during reproduction is 14 to 29 degrees Celsius. Once brown bullhead egg clusters are released and fertilized, they take up to 13 days to hatch, but did so on average at day 5.6 during a study by Blumer (1985). Egg diameter is about 2.2 to 2.7 mm. The larval stage lasts 4 to 9 days, but on average lasted 4.4 days in Blumer's study (1985). Hatched larvae are 4 to 8 mm long, lay on nests during early development, and survive on their yolk-sacs. Metamorphosis occurs between the larval and juvenile stage. Juveniles remain in schools. The average length of the juvenile stage to the end of parental care is 5 days. (Becker, 1983; Blumer, 1985; Eycleshymer, 1901)


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. (Becker, 1983; Blumer, 1985; Encyclopedia of Life, 2010)

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. (Barnes and Hicks, 2003; Becker, 1983; Blumer, 1985; Eycleshymer, 1901; Michigan Department of Natural Resources and Environment, 2010)

  • 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

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. (Becker, 1983; Blumer, 1985; Blumer, 1986a; Blumer, 1986b)

  • 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


Brown bullhead live 6 to 8 years. Maximum age of brown bullhead is 9 years. Predation pressure is strongest during the egg and larval stages. (Blumer, 1986b; Froese and Pauly, 2010; Michigan Department of Natural Resources and Environment, 2010)

  • Range lifespan
    Status: wild
    9 (high) years
  • Average lifespan
    Status: wild
    6 to 8 years


Brown bullhead are a non-migratory species. They are social fish that spend time in schools. (Blazer, et al., 2009a; Blazer, et al., 2009b)

Home Range

Home range sizes of brown bullheads are not reported.

Communication and Perception

Brown bullhead are notable for their sound production, likely produced by rubbing body parts together. In the lab, they produce sound during aggressive, conspecific encounters. Sound production, thought to be a response to disturbances, was recorded in the field and identified with captured fish. Grouped in the superorder Ostariophysi, they share the derived trait of the alarm response (Shreckstoff). (Anderson, et al., 2008; Fine, et al., 1997; Helfman, et al., 2009)

Food Habits

Brown bullhead are benthic, opportunistic omnivores. In aquarium settings they eat most food given to them. Juveniles eat zooplankton, including chironomids, cladocerans, ostracods, and amphipods, insects, including mayfly larvae and caddisfly larvae, and plants. Adults feed on insects, small fish, fish eggs, mollusks, plants, leeches, worms, and crayfish. They typically are nocturnal feeders, but have been observed feeding during the day. They use their barbels to locate food. (Barnes and Hicks, 2003; Becker, 1983; Fisheries and Oceans Canada, 2010; Froese and Pauly, 2010; Kline and Wood, 1996; Raney and Webster, 1940)

  • Animal Foods
  • fish
  • eggs
  • insects
  • mollusks
  • terrestrial worms
  • aquatic or marine worms
  • aquatic crustaceans
  • zooplankton


Predators of brown bullhead include northern pike (Esox lucius), muskellunge (Esox masquinongy), walleye (Sander vitreus), snapping turtles (Chelydra serpentina), water snakes (Nerodia species), and green herons (Butorides virescens). Minnows (Pimephales and Notropis species), yellow perch (Perca flavescens), and sunfishes (Lepomis species) are the most common predators on eggs. (Becker, 1983; Blumer, 1986b; Michigan Department of Natural Resources and Environment, 2010)

  • Anti-predator Adaptations
  • cryptic

Ecosystem Roles

Brown bullhead are predatory fish and prey on other animals.

Economic Importance for Humans: Positive

Brown bullhead are the subject of a small scale recreational and commercial fishery in Canada and in the United States. They have been important research animals for the study of sensory hair cells as well as physiological changes due to temperature, taste, oxygen usage, and osmoregulation. They are also an important indicator species in pollution studies. (Becker, 1983; Blazer, et al., 2009a; Blazer, et al., 2009b; Bowen, 1931; Christensen, et al., 1972; Fisheries and Oceans Canada, 2010; Lesko, et al., 1996; Michigan Department of Natural Resources and Environment, 2010; Sakaris and Jesien, 2005; West, et al., 2006)

  • Positive Impacts
  • food
  • research and education

Economic Importance for Humans: Negative

There are no known adverse effects of brown bullhead on humans.

Conservation Status

Brown bullhead are not listed for protection under the IUCN Red List, the United States Endangered Species Program, or under a CITES appendix. (International Union for Conservation of Nature and Natural Resources, 2009; U.S. Fish & Wildlife Service, 2010; United Nations Environment Programme and World Conservation Monitoring Centre, 2010)


Rachael Guth (author), Northern Michigan University, Rachelle Sterling (editor), Special Projects, Jill Leonard (editor), Northern Michigan University, Tanya Dewey (editor), University of Michigan-Ann Arbor.



Living in Australia, New Zealand, Tasmania, New Guinea and associated islands.

World Map


living in the Nearctic biogeographic province, the northern part of the New World. This includes Greenland, the Canadian Arctic islands, and all of the North American as far south as the highlands of central Mexico.

World Map


living in the northern part of the Old World. In otherwords, Europe and Asia and northern Africa.

World Map


uses sound to communicate


Referring to an animal that lives on or near the bottom of a body of water. Also an aquatic biome consisting of the ocean bottom below the pelagic and coastal zones. Bottom habitats in the very deepest oceans (below 9000 m) are sometimes referred to as the abyssal zone. see also oceanic vent.

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.

brackish water

areas with salty water, usually in coastal marshes and estuaries.


an animal that mainly eats meat


uses smells or other chemicals to communicate


having markings, coloration, shapes, or other features that cause an animal to be camouflaged in its natural environment; being difficult to see or otherwise detect.


animals which must use heat acquired from the environment and behavioral adaptations to regulate body temperature

external fertilization

fertilization takes place outside the female's body

female parental care

parental care is carried out by females


union of egg and spermatozoan


A substance that provides both nutrients and energy to a living thing.


mainly lives in water that is not salty.


having a body temperature that fluctuates with that of the immediate environment; having no mechanism or a poorly developed mechanism for regulating internal body temperature.

indeterminate growth

Animals with indeterminate growth continue to grow throughout their lives.


referring to animal species that have been transported to and established populations in regions outside of their natural range, usually through human action.


offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).


seaweed. Algae that are large and photosynthetic.

male parental care

parental care is carried out by males


A large change in the shape or structure of an animal that happens as the animal grows. In insects, "incomplete metamorphosis" is when young animals are similar to adults and change gradually into the adult form, and "complete metamorphosis" is when there is a profound change between larval and adult forms. Butterflies have complete metamorphosis, grasshoppers have incomplete metamorphosis.


Having one mate at a time.


having the capacity to move from one place to another.


specialized for swimming

native range

the area in which the animal is naturally found, the region in which it is endemic.


active during the night


an animal that mainly eats all kinds of things, including plants and animals


reproduction in which eggs are released by the female; development of offspring occurs outside the mother's body.


an animal that mainly eats fish

seasonal breeding

breeding is confined to a particular season


remains in the same area


reproduction that includes combining the genetic contribution of two individuals, a male and a female


associates with others of its species; forms social groups.


uses touch to communicate


that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).


defends an area within the home range, occupied by a single animals or group of animals of the same species and held through overt defense, display, or advertisement


the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.


uses sight to communicate


animal constituent of plankton; mainly small crustaceans and fish larvae. (Compare to phytoplankton.)


American Fisheries Society, 2004. Common and scientific names of fishes from the United States, Canada, and Mexico. Bethesda: American Fisheries Society.

Anderson, K., R. Rountree, F. Juanes. 2008. Soniferous fishes in the Hudson River. Transactions of the American Fisheries Society, 137: 616-626.

Baily, R., W. Latta, G. Smith. 2004. An atlas of Michigan fishes with keys and illustrations for their identification. Ann Arbor: Museum of Zoology, University of Michigan.

Barnes, G., B. Hicks. 2003. Brown bullhead catfish in Lake Taupo. DOC workshop: 27-35.

Becker, G. 1983. Fishes of Wisconsin. Madison: University of Wisconsin Press.

Blazer, V., J. Fournie, J. Wolf, M. Wolfe. 2006. Diagnostic criteria for proliferative hepatic lesions in brown bullhead Ameiurus nebulosus. Diseases of Aquatic Organisms, 72: 19-30.

Blazer, V., S. Rafferty, P. Baumann, S. Smith, E. Obert. 2009. Assessment of the "fish tumors or other deformities" beneficial use impairments in brown bullhead (Ameiurus nebulosus): I. Orocutaneous tumors. Journal of Great Lakes Research, 35: 517-526.

Blazer, V., S. Rafferty, P. Baumann, S. Smith, E. Obert. 2009. Assessment of the "fish tumors or other deformities" beneficial use impairments in brown bullhead (Ameiurus nebulosus): II. Liver neoplasia. Journal of Great Lakes Research, 35: 527-537.

Blumer, L. 1986. Parental care sex differences in the brown bullhead, Ictalurus nebulosus, (Pisces, Ictaluridae). Behavioral Ecology and Sociobiology, 19: 97-104.

Blumer, L. 1985. Reproductive natural history of the brown bullhead Ictalurus nebulosus in Michigan. American Midland Naturalist, 1985: 318-330.

Blumer, L. 1986. The function of parental care in the brown bullhead Ictalurus nebulosus. American Midland Naturalist, 115: 234-238.

Bowen, R. 1931. Movement of the so-called hairs in the ampullar organs of fish ears. Proceedings of the National Academy of Science, 17: 192-194.

Christensen, G., J. McKim, E. Hunt. 1972. Changes in the blood of the brown bullhead (Ictalurus nebulosus (Lesueur)) following short and long term exposure to copper (II). Toxicology and Applied Pharmacology, 23: 417-427.

Encyclopedia of Life, 2010. "Encyclopedia of Life" (On-line). Accessed February 25, 2010 at http.//

Eycleshymer, A. 1901. Observation on the breeding habits of Ameiurus nebulosus. The American Naturalist, 35: 911-918.

Fine, M., J. Friel, D. McElroy, C. King, K. Loesser, S. Newton. 1997. Pectoral spine locking and sound production in the channel catfish Ictalurus punctatus. Copeia, 1997: 777-790.

Fisheries and Oceans Canada, 2010. "Ontario-Great Lakes area fact sheets" (On-line). Accessed March 09, 2010 at

Froese, R., D. Pauly. 2010. "FishBase" (On-line). Accessed February 25, 2010 at

Hardman, M., L. Page. 2003. Phylogenetic relationships among bullhead catfishes of the Genus Ameiurus (Siluriformes: Ictaluridae). Copeia, 2003: 20-33.

Helfman, G., B. Collette, D. Facey, B. Bowen. 2009. The diversity of fishes. United Kingdom: Wiley-Blackwell Publication.

International Union for Conservation of Nature and Natural Resources, 2009. "IUCN Red List of Threatened Species" (On-line). Accessed March 08, 2010 at

Kline, J., B. Wood. 1996. Food habits and diet selectivity of the brown bullhead. Journal of Freshwater Ecology, 11: 145.

Lesko, L., S. Smith, M. Blouin. 1996. The effects of contaminated sediments on fecundity of the brown bullhead in three Lake Erie tributaries. Journal of Great Lakes Research, 22: 830-837.

Michigan Department of Natural Resources and Environment, 2010. "Natural resources-fishing" (On-line). Accessed March 09, 2010 at

Nelson, J. 1984. Fishes of the world. New York: Wiley-Interscience Publication.

Page, L., B. Burr. 1991. Peterson field guide-freshwater fishes. Boston: Houghton Mifflin Company.

Raney, E., D. Webster. 1940. The food and growth of the young of the common bullhead, Ameiurus nebulosus nebulosus (LeSueur). Transactions of the American Fisheries Society, 69: 205-209.

Rasquin, P. 1949. Spontaneous depigmentation in the catfish. Copeia, 1949: 246-251.

Sakaris, P., R. Jesien. 2005. Brown bullhead as an indicator species: seasonal movement patterns and home ranges within the Anacostia River, Washington, D.C.. Transactions of the American Fisheries Society, 134: 1262-1270.

Tomelleri, J., M. Eberle. 1990. Fishes of the Central United States. Lawrence: University Press of Kansas.

U.S. Fish & Wildlife Service, 2010. "USFWS Endangered Species Program" (On-line). Accessed March 08, 2010 at

United Nations Environment Programme, , World Conservation Monitoring Centre. 2010. "CITES Species Database" (On-line). Accessed March 08, 2010 at

University of Wisconsin Center for Limnology, , Wisconsin DNR, Wisconsin Sea Grant. 2010. "Wisconsin Fish" (On-line). Accessed February 25, 2010 at

West, D., N. Ling, B. Hicks, L. Tremblay, N. Kim, M. Van Den Heuvel. 2006. Cumulative impacts assessment along a large river, using brown bullhead catfish (Ameiurus nebulosus) populations. Environmental Toxicology and Chemistry, 25: 1868-1880.