Invasion History

First Non-native North American Tidal Record: 1894
First Non-native West Coast Tidal Record: 1894
First Non-native East/Gulf Coast Tidal Record:

General Invasion History:

Black Bullheads (Ameiurus melas) are native to the interior basins of North America from southern Saskatchewan and Manitoba to Lake Ontario, south to the Gulf of Mexico coast Louisiana and Texas (Page and Burr 1991; USGS Nonindigenous Aquatic Species Program 2014). They have been introduced to San Francisco Bay and the Columbia River, but the dates of introduction are uncertain because of early confusion of the species introduced in the 19th century (Smith 1895; Lampman 1946; Moyle 2002; Systma et al. 2004). There are also scattered introductions in Atlantic Slope drainages, however, we have not found estuarine records (Daniels et al. 2005; Whitworth 1996; Daniels et al. 2005; (USGS Nonindigenous Aquatic Species Program 2014). North American bullheads (both A. melas and A. nebulosus) have been introduced to freshwaters in Europe, again with confusion on species identity (Copp et al. 2016). Black Bullheads have also been introduced to Puerto Rico, Mexico, and Chile (Lever 1996).

North American Invasion History:

Invasion History on the West Coast:

Black Bullheads may have been introduced to California as early as 1874, with the mixture of White Catfish (Ameiurus catus) from the Atlantic Coast, 'Horned Pout' (Brown Bullhead, A. nebulosus) from Lake Champlain and 'Mississippi catfish' from Nebraska into the Sacramento River (Smith 1895). Black Bullheads were first confirmed in the Kern River in 1940. Later catches were made in the Colorado River in 1942, Modoc County (1942) and near Fresno in 1944. These probably resulted from several separate introductions. In 1952, Black Bullheads were reported from the Sacramento-San Joaquin Delta where they were much less abundant than the White Catfish and Brown Bullhead (Pelgen 1952, cited by Dill and Cordone 1997, Cohen and Carlton 1995; Dill and Cordone 1997; Moyle 2002; Feyrer and Healy 2002; Brown and Michniuk 2007; Grimaldo et al. 2012; Sommer et al. 2014). They have also been collected in the fresh-brackish Suisun Marsh (Matern et al. 2002).

Black Bullheads were reported in the Columbia River (Lamaman 1946; USGS Nonindigenous Aquatic Species Program 2014), but specific records of capture are not available (Systma et al. 2004). Confusing things more, the identity and source of the catfish introduced to the Columbia River is muddled, but one specimen from the Willamette River in 1894 was identified as a Black Bullhead (Smith 1895). They were not reported in a couple of surveys from the Columbia and Willamette Rivers in the vicinity of Portland (Hughes and Gamon 1987; Far and Ward 1994) but were collected in 2008 by Van Dyke et al. (2009) in the Columbia Slough, together with Yellow and Brown Bullheads.

Invasion History on the East Coast:

On the East Coast, there are reports of Black Bullheads in the Connecticut and Hudson River basins, but not established populations (Whitworth 1996; Daniels et al. 2005). There are several populations established in Piedmont reservoirs in Virginia, South Carolina and Georgia, but not near tidal waters (USGS Nonindigenous Aquatic Species Program 2018).

Invasion History Elsewhere in the World:

Black Bullheads were introduced to Puerto Rico (establishment unknown, collected 2004-2007, USGS Nonindigenous Aquatic Species Program 2018), and to Chile (1902), where they are established in the estuary of the Angostura River (Lever 1996; Froese and Pauly 2008). Both Black and Brown Bullheads were extensively introduced to Europe, often with confusion on their identity. In a recent review, Copp et al. (2016) lists 17 European countries with established populations of Black Bullheads. Between 1871 and 1950, both Black and Brown Bullheads were introduced from the United States to different European countries, and transferred between countries. Early introductions of Black Bullheads were made to France in 1885 (Lever 1996) and Spain in the early 1900s. An estuarine population was discovered in the Guadalquivir River estuary in 2007, occurring mostly in the upper estuary at salinities below 5 PSU (Garcia-de-Lomas et al. 2009). Black Bullheads are now considered an undesirable introduction because of their tolerance to polluted conditions, their nest guarding habits (unusual in European freshwater fishes), and their tendency to develop dense populations of stunted fish (Copp et al. 2016).


Black Bullheads (Ameiurus melas) are freshwater fish in the family Ictaluridae, Bullhead Catfishes. Fish in this family have four pairs of barbels, no scales, an adipose fin, stout spines at the origins of the dorsal and pectoral fins, and abdominal pelvic fins. The caudal fin of the Black Bullhead is very slightly notched. The base of the anal fin is relatively short, and rounded with 19-23 rays, with the anterior rays shorter than the posterior ones. The dorsal fin has one spine and six rays. The rear edge of the pectoral spines usually lacks saw-like teeth. Adults can reach 620 mm but are usually below 200 mm. Black Bullheads are dark olive, yellow-brown, or slate-olive, and lighter, often shiny-green-gold on the sides, and white to yellow below, with dusky to black fins. The chin barbels are dusky or dark, (Page and Burr 1991; Jenkins and Burkhead 1993; Moyle 2002).


Taxonomic Tree

Kingdom:   Animalia
Phylum:   Chordata
Subphylum:   Vertebrata
Superclass:   Osteichthyes
Class:   Actinopterygii
Subclass:   Neopterygii
Infraclass:   Teleostei
Superorder:   Ostariophysi
Order:   Siluriformes
Family:   Ictaluridae
Genus:   Ameiurus
Species:   melas


Ictalurus melas (, None)
Silurus melas (Rafinesque, 1820)
Ameiurus vulgaris (Thompson, 1843)

Potentially Misidentified Species

Ameiurus catus
Ameiurus catus (White Catfish) is native to the Atlantic Slope, and has been introduced to the San Francisco estuary and the Columbia River. The tail is forked, the pectoral spine has saw-like teeth, and the chin barbels are white (Page and Burr 1991).

Ameiurus natalis
Ameiurus natalis (Yellow Bullhead) is native to the Atlantic Slope and Mississippi-Great Lakes basin, and has been introduced to the San Francisco estuary and the Columbia River. The tail is squared-off, the pectoral spine has saw-like teeth, and the chin barbels are white or yellow (Page and Burr 1991).

Ameiurus nebulosus
Ameiurus nebulosus (Brown Bullhead) is native to the Atlantic Slope and Mississippi-Great Lakes basin, and has been introduced to the San Francisco estuary and the Columbia River and Fraser Rivers. The tail is squared-off, the pectoral spine has saw-like teeth, and the chin barbels are dark. The body has dark brown mottling (Page and Burr 1991).

Ictalurus furcatus
Ictalurus furcatus (Blue Catfish) are native to the Mississippi-Gulf Basin, and has been introduced, but is rare, in the San Francisco estuary. Adults are very large, and bluish gray in color, without dark mottling. The caudal fin is deeply forked and the anal fin has a straight edge but is tapered posteriorly (Page and Burr 1991).

Ictalurus punctatus
Ictalurus punctatus (Channel Catfish) are native to the Mississippi-Gulf Basin, and the southeastern Coastal Plain, and have been introduced to the San Francisco estuary and the Columbia River. Adults are large and gray in color, with scattered dark spots. The caudal fin is deeply forked and the anal fin has a curved edge (Page and Burr 1991).



The Black Bullheads (Ameiurus melas) are freshwater catfish. Male and female bullheads do not have obvious morphological differences. Black Bullheads vary greatly in growth and life history according to environment and crowding. In different European populations, ponds, lakes, and streams of different sizes, mean age at maturity varied from 52 mm to 155 mm and 1.0 to 3.4 years for females, and 63 to 135 mm and 1.0 to 3.6 years for males (Copp et al. 2016). Spawning occurs at 21-30 C (Jenkins and Burkhead 1993). The female excavates a shallow nest in the substrate by fanning away debris and pushing it away with her snout. Females contain 1251-6820 eggs (Copp et al. 2016). During spawning, the male and female embrace in a head-to-tail fashion, with the males' tail curled around the female's head. The eggs are usually guarded by the male, but sometimes by both parents. Prolarvae remain in the nest until the yolk-sac is absorbed. When the yolk-sac is absorbed, fin-ray development is complete, and the fish are juveniles, Like other bullheads, the juveniles swim in dense schools in shallow water (Wang 1986)

Black Bullheads range from cold-temperate to subtropical climates, and tolerate temperatures from near 0 C in ice-covered rivers in winter, to 30 C (Froese and Pauly 2018). Adults tolerate salinities up to 10 PSU in the field (Chipman 1959, cited by Kendall and Schwartz 1968). Their habitat includes 'pools, backwaters, and slow currents over soft substrates in creeks and small to large rivers, impoundments, oxbows, and ponds (Page and Burr 1991). Adults were common in the dead-end sloughs of the Delta, such as Hog, Sycamore, and Indian Sloughs (Turner 1966a, cited by Wang 1986). Black Bullheads are omnivorous and eat aquatic plants, benthic invertebrates, and small fishes (Jenkins and Burkhead 1993; Moyle 2002). Predators include larger fish, birds, and humans.


insects, invertebrates, plants

Trophic Status:




General HabitatNontidal FreshwaterNone
General HabitatFresh (nontidal) MarshNone
General HabitatGrass BedNone
General HabitatCoarse Woody DebrisNone
General HabitatSwampNone
General HabitatTidal Fresh MarshNone
General HabitatUnstructured BottomNone
Salinity RangeLimnetic0-0.5 PSU
Salinity RangeOligohaline0.5-5 PSU
Tidal RangeSubtidalNone
Vertical HabitatNektonicNone
Vertical HabitatEpibenthicNone

Tolerances and Life History Parameters

Minimum Temperature (ºC)0Based on geographical range
Maximum Temperature (ºC)30Field, Froese and Pauly 2008
Minimum Salinity (‰)0Freshwater species
Maximum Salinity (‰)10Chipman 1959. cited by Kendall and Schwartz 1968
Minimum Reproductive Temperature21Field, Jenkins and Burkhead 1993
Maximum Reproductive Temperature30Field, Jenkins and Burkhead 1993
Minimum Length (mm)52For a female from a stunted populaiton, more frequently 90 to 130 mm (Copp et al. 2016).
Maximum Length (mm)620Page and Burr 1991, but more usually 150-300 (Jenkins and Burkehead 1993; Copp et al. 2016).

General Impacts

Black Bullheads (Ameiurus melas) are rare in the San Francisco and Columbia estuaries, and probably have minimal ecological and economic impacts. In Europe, where they are widely introduced, they are regarded as an undesirable introduction, because of their tendency to develop dense populations, and to create turbidity during feeding. In Europe, nest guarding, and territoriality is an unusual habit in European fishes, and deprives native species of space for foraging (Copp et al. 2016). An introduced population in the Guadalquivir estuary, Spain, is considered a threat to fisheries and aquaculture (Garcia-de-Lomas et al. 2009).

Regional Distribution Map

Bioregion Region Name Year Invasion Status Population Status
P260 Columbia River 1894 Def Estab
P090 San Francisco Bay 1952 Def Estab
G150 Mobile Bay 0 Native Estab
G160 East Mississippi Sound 0 Native Estab
G170 West Mississippi Sound 0 Native Estab
G180 Breton/Chandeleur Sound 0 Native Estab
G190 Mississippi River 0 Native Estab
G210 Terrebonne/Timbalier Bays 0 Native Estab
G220 Atchafalaya/Vermilion Bays 0 Native Estab
G230 Mermentau River 0 Native Estab
G200 Barataria Bay 0 Native Estab
G240 Calcasieu Lake 0 Native Estab
G250 Sabine Lake 0 Native Estab
G260 Galveston Bay 0 Native Estab
G270 Brazos River 0 Native Estab
G280 Matagorda Bay 0 Native Estab
G290 San Antonio Bay 0 Native Estab
G300 Aransas Bay 0 Native Estab
G310 Corpus Christi Bay 0 Native Estab
G320 Upper Laguna Madre 0 Native Estab
G330 Lower Laguna Madre 0 Native Estab
GL-I Lakes Huron, Superior and Michigan 0 Native Estab
GL-II Lake Erie 0 Native Estab
GL-III Lake Ontario 0 Native Estab
P023 _CDA_P023 (San Louis Rey-Escondido) 1974 Def Estab

Occurrence Map

OCC_ID Author Year Date Locality Status Latitude Longitude


Brown, Larry R.; Michniuk, Dennis (2007) Littoral fish assemblages of the alien-dominated Sacramento-San Joaquin Delta, California, 1980-1983 and 2001-2003., Estuaries and Coasts 90: 186-200

Cohen, Andrew N.; Carlton, James T. (1995) Nonindigenous aquatic species in a United States estuary: a case study of the biological invasions of the San Francisco Bay and Delta., U.S. Fish and Wildlife Service and National Sea Grant College Program (Connecticut Sea Grant), Washington DC, Silver Spring MD.. Pp. <missing location>

Daniels, Robert A.; Limburg, Karin E.; Schmidt, Robert E; Strayer, David L.; Chambers, R. Christopher (2005) Changes in fish assemblages in the tidal Hudson river, New York., American Fisheries Society Symposium 45: 471-503

Dill, William A.; Cordone, Almo J. (1997) History and status of introduced fishes in California, 1871-1996, California Department of Fish and Game Fish Bulletin 178: 1-414

Farr, Ruth A., Ward, David L. (1992) Fishes of the lower Willamette River, near Portland, Oregon, Northwest Science 67(1): 16-22

Feyrer, Frederick; Healey, Michael P. (2003) Fish community structure and environmental correlates in the highly altered southern Sacramento-San Joaquin Delta., Environmental Biology of Fishes 66: 123-132

2002-2014 FishBase.(World Wide Web electronic publication)..

Grimaldo, Lenny; Miller, Robert E.; Hymanson, ZacharyPeregrin, Chris M., (2012) Fish assemblages in reference and restored tidal freshwater marshes of the San Francisco estuary, San Francisco Estuary and Watershed Science 10(1):

Hughes, Robert M., Gammon, James R. (1987) Longitudinal changes in fish assemblages and water quality in the Willamette River, Oregon, Transactions of the American Fisheries Society 116: 196-209

Jenkins, Robert E.; Burkhead, Noel M. (1993) Freshwater Fishes of Virginia, American Fisheries Society, Bethesda, MD. Pp. <missing location>

Lampman, Ben Hur (1946) Coming of the Pond Fishes, Binfords & Mort, Portland, OR. Pp. <missing location>

Lee, David S.; Gilbert, Carter R.; Hocutt, Charles H.; Jenkins, Robert E.; McAllister, Don E.; Stauffer, Jay R. (1980) Atlas of North American freshwater fishes, North Carolina State Museum of Natural History, Raleigh. Pp. <missing location>

Lever, Christopher (1996) Naturalized fishes of the world, Academic Press, London. Pp. <missing location>

Matern, Scott A.; Moyle, Peter; Pierce, Leslie C. (2002) Native and alien fishes in a California estuarine marsh: twenty-one years of changing assemblages, Transactions of the American Fisheries Society 131: 797-816

Page, Lawrence M.; Burr, Brooks M. (1991) Freshwater Fishes: North America North of Mexico, Houghton-Mifflin, Boston. Pp. <missing location>

Simon, Carol A.; van Niekerk, H. Helene; Burghardt, Ingo; ten Hove, Harry A.; Kupriyanova, Elena K. (2019) Not out of Africa: Spirobranchus kraussii (Baird, 1865) is not a global fouling and invasive serpulid of Indo-Pacific origin, Biological Invasions 14(3): 221–249.

Smith, Hugh M. (1895) A review of the history and results of the attempts to acclimatize fish and other water animals in the Pacific states., Bulletin of the U. S. Fish Commission 15: 379-472

Sytsma, Mark D.; Cordell, Jeffrey R.; Chapman, John W.; Draheim, Robyn, C. (2004) <missing title>, Center for Lakes and Reservoirs, Portland State University, Portland OR. Pp. <missing location>

2003-2015 Nonindigenous Aquatic Species Database. Gainesville, FL.

Wang, Johnson C. S. (1986) Fishes of the Sacramento - San Joaquin Estuary and Adjacent Waters, California: A Guide to the Early Life Histories, IEP Technical Reports 9: 1-673

Whitworth, Walter R. (1968) Freshwater fishes of Connecticut, Bulletin, State Geological and Natural History Survey of Connecticut 101: 1-134