Invasion History

First Non-native North American Tidal Record: 1905
First Non-native West Coast Tidal Record: 1905
First Non-native East/Gulf Coast Tidal Record:

General Invasion History:

Yellow Bullheads (Ameiurus natalis) are freshwater catfish native to interior basins of North America from the St. Lawrence River-Lake Champlain west to North Dakota and south to Florida and Texas. On the Atlantic coast, they are native from southern Florida to the Hudson River (Page and Burr 1991; USGS Nonindigenous Aquatic Species Program 2014). They have been introduced to Atlantic drainages in Connecticut and Massachusetts (USGS Nonindigenous Aquatic Species Program 2014), but we have no reports from estuaries in New England. Yellow Bullheads have been widely introduced in the western United States, establishing in the Colorado River, and the Columbia River estuary. Their establishment in the Sacramento-San Joaquin Delta is somewhat uncertain (Dill and Cordone 1997; Moyle 2002; Leidy 2007), but they were reported in a recent survey (Sommer et al. 2014).

North American Invasion History:

Invasion History on the West Coast:

Yellow Bullheads (Ameiurus natalis) may have been included in mixed shipments of 'catfishes' to California in 1874, and to Oregon in 1888-1905. However, they are easily confused with Black Bullheads (I. melas) and Brown Bullheads (I. nebulosus) (Smith 1895; Chapman 1943; Lampman 1946; Dill and Cordone 1997). The first definite California record was from the Colorado River in 1942. Soon after in 1944, they were found in the Sacramento-San Joaquin Delta and from streams and freshwater sloughs in the Delta (Dill and Cordone 1997; Moyle 2002), but were not found in other surveys (Leidy 2007). Small numbers were found in a 1999-2006 survey of fishes of the Yolo Bypass (Sommer et al. 2014), so we treat them as 'established'.

As in California, introductions of unidentified catfishes in the Columbia River occurred in the late 19th century, before accurate identifications were made. Sytsma et al. (2004) gave the date of introduction as 1905, when a large exhibit of Mid-Western 'spiny rayed fishes' was released into a pond along the Columbia River, during the Lewis and Clark Centennial Exhibition (Lampman 1946). However, the first definite identification of the Yellow Bullhead in the Columbia and Willamette Rivers was in 1945 (Lampman 1946). They were found in recent surveys of the rivers and sloughs around Portland but were less abundant than the Black Bullhead (Hughes and Gammon 1987; Farr and Ward 1993; Van Dyke et al. 2009). In 2005, one specimen was collected in British Columbia, in Siverment Lake, adjacent to the lower Fraser River (Hanke et al. 2006).


The Yellow Bullhead (Ameiurus natalis) is a freshwater fish. Bullhead Catfishes (Ictaluridae) 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 Yellow Bullhead is rounded or nearly straight. The anal fin is moderately long and nearly straight in outline, with 24-27 rays. The dorsal fin has one spine and 6 rays. The rear edge of the pectoral spines has 5-8 saw-like teeth. Adults can reach 470 mm, but more usually below 200 mm. Yellow Bullheads are olive to slate-black above, or slate-olive, and lighter, yellow-olive on the sides, and white to yellow below, with dusky to black fins. The chin barbels are white (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:   natalis


Ictalurus natalis (, None)
Pimelodus natalis (Leseur, 1819)

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 melas
Ameiurus melas (Black Bullhead) is native to the 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 lacks sawlike teeth, and the chin barbels are dark (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 has been introduced to the San Francisco estuary and the Columbia River. Adults are large, gray in color, without scattered dark spots. The caudal fin is deeply forked, and the anal fin has a curved edge (Page and Burr 1991).



Yellow Bullheads (Ameiurus natalis) are freshwater catfish. Male and female bullheads do not have obvious morphological differences. They mature in the second or third year, at a minimum of 127 mm. Spawning occurs in spring. Both parents excavate a shallow circular nest in the substrate by fanning away debris and pushing it away with their snouts. Females contain 1650-7000 eggs. 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. Prolarvae remain in the nest until the yolk-sac is absorbed (Jones et al. 1978; Jenkins and Burkhead 1994. 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 (Jones et al. 1978).

Yellow Bullhead are warm-water fish and range from cold-temperate to subtropical climates. Adults tolerate salinities up to 15 PSU but is rare at salinities above 5 PSU (Kilby 1955, cited by Kendall and Schwartz 1968; Murdy et al. 1997). Their habitats include 'pools, backwaters, and sluggish currents over soft substrates in creeks and small to large rivers, impoundments, oxbows, and ponds' (Page and Burr 1991). Yellow Bullheads are omnivorous and eat aquatic plants, benthic invertebrates, and small fishes (Murdy et al. 1997). Predators include larger fish, birds, and humans.


Insects, mollusks, crustaceans, plants

Trophic Status:




General HabitatFresh (nontidal) MarshNone
General HabitatNontidal FreshwaterNone
General HabitatGrass BedNone
General HabitatCoarse Woody DebrisNone
General HabitatSwampNone
General HabitatTidal Fresh MarshNone
Salinity RangeLimnetic0-0.5 PSU
Salinity RangeOligohaline0.5-5 PSU
Salinity RangeMesohaline5-18 PSU
Tidal RangeSubtidalNone
Vertical HabitatNektonicNone
Vertical HabitatEpibenthicNone

Tolerances and Life History Parameters

Minimum Temperature (ºC)0Based on range
Minimum Salinity (‰)0Freshwater species
Maximum Salinity (‰)15Kilby1955, cited by Kendall and Schwartz (1968). However, it rarely occurs at salinities above 5 PSU (Murdy et al. 1997).
Maximum Length (mm)465Jenkins and Burkhead 1993

General Impacts

Yellow Bullheads (Ameiurus natalis) are apparently very rare in the San Francisco estuary, and uncommon in the Columbia River estuary (Moyle 2002; Farr and Ward 1994; Van Dyke et al. 2009). No Impacts have been reported.

Regional Distribution Map

Bioregion Region Name Year Invasion Status Population Status
P260 Columbia River 1905 Def Estab
P090 San Francisco Bay 1944 Def Estab
M060 Hudson River/Raritan Bay 0 Native Estab
M090 Delaware Bay 0 Native Estab
M130 Chesapeake Bay 0 Native Estab
S010 Albemarle Sound 0 Native Estab
S020 Pamlico Sound 0 Native Estab
S050 Cape Fear River 0 Native Estab
S030 Bogue Sound 0 Native Estab
S040 New River 0 Native Estab
S060 Winyah Bay 0 Native Estab
S070 North/South Santee Rivers 0 Native Estab
S080 Charleston Harbor 0 Native Estab
S090 Stono/North Edisto Rivers 0 Native Estab
S100 St. Helena Sound 0 Native Estab
S110 Broad River 0 Native Estab
S120 Savannah River 0 Native Estab
S130 Ossabaw Sound 0 Native Estab
S140 St. Catherines/Sapelo Sounds 0 Native Estab
S150 Altamaha River 0 Native Estab
S160 St. Andrew/St. Simons Sounds 0 Native Estab
S170 St. Marys River/Cumberland Sound 0 Native Estab
S180 St. Johns River 0 Native Estab
S183 _CDA_S183 (Daytona-St. Augustine) 0 Native Estab
S190 Indian River 0 Native Estab
S196 _CDA_S196 (Cape Canaveral) 0 Native Estab
S200 Biscayne Bay 0 Native Estab
G010 Florida Bay 0 Native Estab
G020 South Ten Thousand Islands 0 Native Estab
G030 North Ten Thousand Islands 0 Native Estab
G045 _CDA_G045 (Big Cypress Swamp) 0 Native Estab
G050 Charlotte Harbor 0 Native Estab
G070 Tampa Bay 0 Native Estab
G074 _CDA_G074 (Crystal-Pithlachascotee) 0 Native Estab
G078 _CDA_G078 (Waccasassa) 0 Native Estab
G076 _CDA_G076 (Withlachoochee) 0 Native Estab
G080 Suwannee River 0 Native Estab
G086 _CDA_G086 (Econfina-Steinhatchee) 0 Native Estab
G090 Apalachee Bay 0 Native Estab
G100 Apalachicola Bay 0 Native Estab
G110 St. Andrew Bay 0 Native Estab
G130 Pensacola Bay 0 Native Estab
G120 Choctawhatchee Bay 0 Native Estab
G140 Perdido Bay 0 Native Estab
G160 East Mississippi Sound 0 Native Estab
G150 Mobile Bay 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
G200 Barataria Bay 0 Native Estab
G220 Atchafalaya/Vermilion Bays 0 Native Estab
G230 Mermentau River 0 Native Estab
G250 Sabine Lake 0 Native Estab
G240 Calcasieu 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
NA-S3 None 0 Native Unk

Occurrence Map

OCC_ID Author Year Date Locality Status Latitude Longitude


Sotka, Erik E.; Bell; Tina; Hughes, Laurn E. ; Lowry, James K.; Poore, Alistair G. B. (2016) A molecular phylogeny of marine amphipods in the herbivorous family Ampithoidae, Zoologica Scripta 46(1): 85-95

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>

Cook Inlet Regional Citizen's Council 2023 Seaweeds of Alaska.

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

Hargrove . John S.; Weyl, Olaf L. F.; Austin, James D. (2017) Reconstructing the introduction history of an invasive fish predator in South Africa, Biological Invasions 19: 2261–2276

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>

Jones, Philip W.; Martin, F. Douglas; Hardy, Jerry D., Jr. (1978) Development of fishes of the mid-Atlantic Bight. V. 1. Acipenseridae through Ictaluridae., In: (Eds.) . , Washington DC. 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>

Leidy, R. A. (2007) <missing title>, San Francisco Estuary Institute, Oakland. Pp. <missing location>

Musick, J. A.; Wiley, Martin L. (1972) Fishes of Chesapeake Bay and the adjacent coastal plain, Special Scientific Report, Virginia Institute of Marine Science 65: 175-212

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

Parsons, Murray J. 1982 Colpomenia (Endlicher) Derbès et Solier (Phaeophyta) in New Zealand.

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>

USGS Nonindigenous Aquatic Species Program 2003-2024 Nonindigenous Aquatic Species Database.

Whitworth, Walter R. (1996) Freshwater fishes of Connecticut, State Geological and Natural History Survey of Connecticut 114: 33-214

Wright, Rosalind; et al. (2022) First direct evidence of adult European eels migrating to their breeding place in the Sargasso Sea, Scientific Reports 3,2(25362): Published online