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      Ameiurus nebulosus (Photo: Noel Burkhead, USGS) - Click for full size   Ameiurus nebulosus (Photo: John Craig Cloutier.  Thanks to the New Hampshire Fish and Game Department for permission to use image. - Click for full size
    Taxonomic name: Ameiurus nebulosus (Lesueur, 1819)
    Synonyms: Ameirus nebulosus (Lesueur, 1819), Ameirus nebulosus Lesueur, 1819, Ameiurus lacustris (Walbaum, 1792), Ameiurus vulgaris (Thompson, 1842), Amiurus catus (Linnaeus, 1758), Amiurus nebulosus (Lesueur, 1819), Amiurus vulgaris (Thompson, 1842), Ictalurus nebulosus marmoratus (Holbrook, 1855), Ictalurus nebulosus nebulosus (Lesueur, 1819), Ictalurus nebulosus pannonicus Harka & Pinter, 1990, Ictalurus nebulosus (Lesueur, 1819), Pimelodus atrarius DeKay, 1842, Pimelodus catus (Linnaeus, 1758), Pimelodus felis Agassiz, 1850, Pimelodus nebulosus Lesueur, 1819, Pimelodus vulgaris Thompson, 1842, Silurus coenosus Richardson, 1836, Silurus felis Linnaeus, 1766, Silurus nigrescens Lesueur
    Common names: barbotte brune (French-Canada), bici-cu-coarne (Romanian), Brauner katzenwels (German-Germany), brown bullhead (English), bruine Amerikaanse dwergmeerval (Dutch), brun dværgmalle (Danish), brun dvärgmal (Swedish), bullhead (English), catfish (English), common bullhead (English), common catfish (English), dværgmalle (Danish), dvärgmal (Swedish), dvergmalle (Norwegian), horned pout (English), hornpout (English), kanalnyi somik (Russian-Ukraine), Katzenwels (German), marbled bullhead (English), minister (English), mudcat (English), northern brown bullhead (English), piikkimonni (Finnish), poisson chat (French), somn American (Romanian), somn pitic (Romanian), sumcek krpatý (Slovak), sumecek americký (Czech), sumik karlowaty (Polish), Zwergwels (German)
    Organism type: fish
    Ameiurus nebulosus, the brown bullhead, is a species of catfish native to North America and introduced to a number of other countries around the world as a game fish. It is a hardy species that can tolerate a wide range of environmental conditions, including water pollution, allowing it to successfully establish outside of its native range. Some concern has been raised over its invasive potential, but there is a lack of information on its effects.
    Description
    McDowall (1990) describes the brown bullhead as a "stout fish with a thick body and ventrally flattened head. The back is moderately arched and there is a distinct hump behind the head. Four pairs of barbels are present around the mouth, with a single long one at each corner of the mouth, a pair in front of the eyes on the snout, and two pairs beneath the chin. The skin is thick and leathery with a layer of mucuous. Scales are absent. Colouration is a dark brown to greenish olive on the back, with slightly paler sides. The underside of the head and lower jaw are a buttery yellow colour, which pales to a creamy white or pale grey on the belly".
    Occurs in:
    lakes, water courses, wetlands
    Habitat description
    Found in sluggish, often weedy, streams and rivers. Also occurs in impoundments, lakes, lagoons and ponds. The brown bullhead can tolerate waters with high carbondioxide and low oxygen concentrations, as well as temperatures up to 31.6°C (FishBase, 2004). It can live out of water for long periods if kept moist (McDowall, 2000).
    General impacts
    Although there is some concern that brown bullheads may negatively affect trout fisheries (Dedual, 2002), freshwater crayfish (Barnes, 1996) and eels (Rowe and Graynoth, 2002) there does not appear to be any hard evidence of environmental impacts caused by this species.
    Uses
    Popular in some areas as a gamefish. Reportedly a good eating fish, especially when smoked (FishBase, 2004).
    Notes
    Resistant to domestic and industrial pollution, therefore able to survive in heavily degraded waters. Reported to bury itself in mud to avoid adverse environmental conditions (FishBase, 2004). Brown bullhead are scavengers as well as predators, locating their prey in the substrate through the use of their sensory barbels (McDowall, 1990). A painful wound can be inflicted by the sharp spines in the fins of brown bullhead catfish if they are not handled carefully. Toxins released by the fish contribute to the pain of the wound (McDowall, 1990).
    Geographical range
    Native range: Native to North America, from Canada to Southern USA.
    Known introduced range: Introduced to many countries throughout Europe, as well as Chile, Puerto Rico and New Zealand (FishBase, 2004).
    Introduction pathways to new locations
    Ignorant possession: Commercial fishermen may inadvertently transport brown bullhead in their nets, as they are able to survive for long periods out of water.
    Stocking: Stocking may occur in locations where brown bullhead is valued as a sport fish.


    Local dispersal methods
    Intentional release: Introduced to many locations as a sport fish through angling organisations.
    Natural dispersal (local): Can expand distribution within connected water bodies through swimming.
    Other (local): Commercial fishermen may inadvertently transport brown bullhead in their nets, as they are able to survive for long periods out of water.
    Management information
    Dedual (2002) suggests that commercial harvesting of brown bullhead using fyke nets in Lake Taupo, New Zealand could be an option if they are found to impact upon trout.
    Nutrition
    Feeds on a wide variety of items including snails, freshwater crayfish, fish eggs, worms, insects (adults and larvae), fish and algae (FishBase, 2004; McDowall, 2000).The main prey of adult brown bull head in Lake Taupo, New Zealand are freshwater crayfish (Barnes, 1996).
    Reproduction
    Spawning occurs in a nest, a shallow depression in the substrate, built by one or both parents. Eggs are guarded, with the attendant fish moving them with its barbels and fanning them with its fins to encourage development. Hatching occurs in around a week, with the young dispersing in small shoals. (FishBase, 2004; McDowall, 2000).
    Lifecycle stages
    Maturity attained at two to three years of age, when around 180-200mm long. Can live for up to eight years (McDowall, 2000).
    Reviewed by: Dr. David Rowe, NIWA (National Institute of Water & Atmospheric Research). Hamilton New Zealand.
    Principal sources: McDowall, R. M., 2000. The Reed field guide to New Zealand freshwater fishes. Auckland, Reed.
    FishBase, 2004. Species profile Ameiurus nebulosus
    McDowall, R. M.1990. New Zealand Freshwater Fish a natural history and Guide. Heinmann and Reed MAF Publishing Group.
    Barnes, G.E., 1996. The biology and general ecology of the brown bull head catfish (Ameiurus nebulosus) in Lake Taupo. MSc Thesis, University of Waikato, Hamilton.
    Rowe, D.K and Graynoth, E, 2002. Lake Managers Handbook- Fish in New Zealand Lakes. Ministry for the Environment, Wellington.
    Compiled by: IUCN/SSC Invasive Species Specialist Group (ISSG) with support from the Terrestrial and Freshwater Biodiversity Information System (TFBIS) Programme (Copyright statement)
    Last Modified: Tuesday, 11 April 2006


ISSG Landcare Research NBII IUCN University of Auckland