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The Nonindigenous Occurrences section of the NAS species profiles has a new structure. The section is now dynamically updated from the NAS database to ensure that it contains the most current and accurate information. Occurrences are summarized in Table 1, alphabetically by state, with years of earliest and most recent observations, and the tally and names of drainages where the species was observed. The table contains hyperlinks to collections tables of specimens based on the states, years, and drainages selected. References to specimens that were not obtained through sighting reports and personal communications are found through the hyperlink in the Table 1 caption or through the individual specimens linked in the collections tables.

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Common name: Flathead Catfish

Synonyms and Other Names: mudfish

Taxonomy: available through www.itis.gov

Identification: Wide, flat head - more so than native catfishes. Yellow to purple-brown dorsal coloration and pale white to yellow belly. Projecting lower jaw, pale tips on tail fin, short anal fin.  Becker (1983); Page and Burr (1991); Etnier and Starnes (1993); Jenkins and Burkhead (1994).Projecting lower jaw, pale tips on tail fin, short anal fin.  Becker (1983); Page and Burr (1991); Etnier and Starnes (1993); Jenkins and Burkhead (1994).

Size: 155 cm (Page and Burr 1991)

Native Range: Mississippi River basin from western Pennsylvania to White-Little Missouri River system, North Dakota, and south to Louisiana; Gulf Slope from Mobile Bay drainage, Georgia and Alabama, to Mexico (Page and Burr 1991).Mississippi River basin from western Pennsylvania to White-Little Missouri River system, North Dakota, and south to Louisiana; Gulf Slope from Mobile Bay drainage, Georgia and Alabama, to Mexico (Page and Burr 1991).
 

Alaska	Hawaii	Puerto Rico & Virgin Islands	Guam Saipan

Native range data for this species provided in part by NatureServe

Hydrologic Unit Codes (HUCs) Explained
Interactive maps: Point Distribution Maps

Ecology: Pylodictis olivaris is found in large rivers, streams, and lakes, usually over hard bottoms. They prefer deep, sluggish pools, with logs and other submerged debris that can be used as cover. Young P. olivaris live in rocky or sandy runs in the river and in riffles, often under stones on riffles (Hubbs et al. 2004; Page and Burr 2011). This species lives in shallower (<3 m) waters in summer/at night and migrates to deeper waters (> 4m) in the day/winter (Daugherty and Sutton 2005). This species benefits from turbid waters as they are a non-sight feeding predator (Ward and Vaage 2019).

Unlike other catfish, Flathead Catfish feed on only live prey. Adult Flathead Catfish are piscivorous ambush predators (Eggleton and Schramm 2004). This species has a diverse diet, feeding on macroinvertebrates and fish, including shads, centrarchids, bass, and crayfish (Schmitt et al. 2019; Montague and Shoup 2021).

Age at sexual maturity appears to be regionally dependent, ranging from 3–5 years for males and 3–7 years for females. Spawning occurs once in late spring to early summer when water temperatures reach 19 to 24 degrees Celsius. One or both parents excavate a nest that is usually made in a natural cavity or near a large submerged object (Jackson 1999). Females lay a mass of up to 100,000 adhesive eggs (Jackson 1999), or 1,637 to 5,025 eggs/kg (Gima 2009). Males guard the nest and agitate the eggs to keep them clean and aerated. The young remain in a school near the nest for several days after hatching, but soon disperse. Flathead Catfish can live up to 28 years (Jackson 1999).

Means of Introduction: The Flathead Catfish has been intentionally stocked in most cases. In Idaho, however, flatheads were accidentally stocked instead of blue catfish (Simpson and Wallace 1978). Populations in the Apalachicola River, Florida, probably spread from introductions upstream in the Flint River, Georgia. It is believed that flatheads were stocked by anglers circa 1950 in the vicinity of Potato Creek in Upson County, Georgia, with stock from the Tennessee drainage (Quinn 1988). They were recorded in the Flint River below the Warwick Dam at Lake Blackshear in the early 1960s, and at Albany in the early 1970s (Quinn 1988). The species was apparently first stocked in the Cape Fear River in 1966 when 11 sexually mature fish were released near Fayetteville, North Carolina, by North Carolina Wildlife Resources Commission biologists (Guire et al. 1984; Ashley and Buff 1986). Flatheads were stocked in Atlantic drainages (Savannah and Altamaha) in Georgia in the 1970s (Bart et al. 1994; C. Jennings, personal communication). According to Bart et al. (1994), at least some of these were the result of stocking by Georgia Department of Natural Resource personnel. The first known reports of this fish in California were recorded catches made in the lower Colorado River near Yuma in 1966 (Dill and Cordone 1997). The Colorado River populations in California and Arizona resulted, at least in part, from a stocking of about 600 Flathead Catfish above Imperial Dam made by the Arizona Game and Fish Department in 1962 (Dill and Cordone 1997). According to Dill and Cordone (1997), the believed route of the Flathead Catfish was downstream to Imperial Dam and subsequently into the All American Canal system to the Imperial Valley. Minckley (1973) reported that the species was introduced prior to 1950 into the Gila River system, a tributary of the Colorado River; however, Dill and Cordone (1997) indicated that the Flathead Catfish was not taken in the lower Colorado River basin until after 1962. A single fish was taken 20 November 1995 in Arizona from the upper San Pedro River, about 32 kilometers from the Mexican border (S. Stefferud, personal communication). It is not known how the species gained access to the upper reach of this river. In Wisconsin, flatheads probably entered the Wolf and Fox drainages via the canal at Portage (Becker 1983). The Ochlockonee River introduction in Florida and Georgia was probably due to illegal stocking by anglers with fish from the nearby Apalachicola River, where the fish had also been introduced. The flathead's presence in eastern Pennsylvania is most likely due to stock contamination of channel catfish shipments (M. Kaufman, personal communication).

Status: Occurs in all U.S. states except Alaska, Hawaii, Montana, Utah and the New England states (Montague and Shoup 2021). The Flathead Catfish has become established in most waters where introduced. For instance, it is widespread and reproducing in the lower Colorado River basin (Dill and Cordone 1997). As of about 1980, the Cape Fear River population had expanded from the site of its initial release near Fayetteville, North Carolina, and was found to inhabit a 201-kilometer stretch of the river (Guire et al. 1984). In samples taken by Guire et al. (1984) from the Cape Fear River, flathead accounted for 10.52% of total fish numbers and 64.7% of total fish weight. Establishment in Oregon is uncertain (Bond 1994). The species does not appear to have survived to reproduce in Wyoming (Hubert 1994). It has been reported from the San Pedro River, Arizona, and from the Suwannee River, Florida. Established in Blue Marsh Reservoir and the Schuylkill River in Pennsylvania; reported in Springton Reservoir, Pennsylvania.

Great Lakes: Reproducing and overwintering in Lakes Erie, Huron, and Michigan.

Impact of Introduction: Many feeding studies have found that Flathead Catfish prey heavily on sunfish Lepomis spp. (Quinn 1988). One study found that they reduced the number of common carp Cyprinus carpio and bullheads Ameiurus spp. (Quinn 1988). However, the introduced population in the Flint River system was found to prey largely on crayfish, and that young-of-the-year flatheads fed on darters Etheostoma spp. clupeids, catostomids, ictalurids (including other flatheads), and centrarchids were also consumed (Quinn 1988). According to Quinn (1988), introduced flatheads in the Flint River rely more on crayfish than any other catfish population yet described. A severe decline in native fish species, particularly native bullhead species, was observed in the Cape Fear River within 15 years of the first Flathead Catfish introduction (Guire et al. 1984; Jenkins and Burkhead 1994). Feeding studies conducted in the Cape Fear River showed that flatheads consume mainly bullheads, catfishes, shad, and sunfishes (Guire et al. 1984; Ashley and Buff 1986). In 1979, flatheads in the Cape Fear River fed primarily on bullheads. However, by 1986, bullhead populations had declined and Flathead Catfish had switched to preying on shad (Ashley and Buff 1986). Diet studies also have been conducted in the Oconee River in Georgia, where this catfish had been implicated in causing declines of native bullheads and sunfishes (especially redbreast sunfish Lepomis auritus). However, findings of that initial study were inconclusive since most of the Flathead Catfish examined had empty stomachs (C. Jennings, personal communication). Flathead Catfish also may be responsible for declines in other native species in the Altamaha drainage (C. Jennings, personal communication). In the Ocmulgee River, Georgia, abundances of silver redhorse Moxostoma anisurum, robust redhorse M. robustum, snail bullhead Ameiurus brunneus, flat bullhead A. platycephalus, and redbreast sunfish Lepomis auritus, were negatively correlated with Flathead Catfish occurrence and abundance (Bart et al. 1994). This correlation may be due to direct predation. Several authors have reported suckers and catfish as common prey items of flatheads (Bart et al. 1994). The snail bullhead and flat bullhead appear to be most affected by the presence of Flathead Catfish in the Ocmulgee drainage (Bart et al. 1994). It is suspected flatheads may be contributing to the decline of the federally threatened Gulf sturgeon Acipenser oxyrinchus desotoi by consuming the young benthic fish in the Apalachicola River (J. Williams, personal communication). The Flathead Catfish is thought to be contributing to the decline of the razorback sucker Xyrauchen texanus. For instance, Marsh and Brooks (1989) found that intensive predation by Flathead Catfish and channel catfish on juvenile razorback suckers is likely to prevent hatchery transplants of this southwestern endangered sucker from becoming re-established in portions of its natural range. If the Flathead Catfish becomes established in the San Pedro River, it could mean a major loss for recovery of several species (S. Stefferud, personal communication). Introductions of Flathead Catfish are probably the most biologically harmful of all fish introductions in North America (C. Gilbert, personal communication). Flathead Catfish, along with other nonnative piscivorous fishes, have been shown to reduce the abundance and diversity of native prey species in several Pacific Northwest rivers (Hughes and Herlihy 2012).

Remarks: The Flathead Catfish became the dominant predator in the Cape Fear drainage of North Carolina within 15 years of the introduction (Guire et al. 1984). The species may actually be native to the upper Tennessee drainage in North Carolina (Jenkins and Starnes, personal communication). In their book on Alabama fishes, Mettee et al. (1996) presented conflicting information regarding native versus introduced ranges. These researchers stated, in the species account, that Pylodictis olivaris is introduced to the Conecuh and Escatawpa river systems, but they listed the species as "native" in their summary table. Starnes et al. (2011) suggest that although the Potomac River population is highly localized, favorable habitat in the Plummers Island area could allow it to expand further upstream.
 
Flathead Catfish was previously suggested as native to the lower Great Lakes (Underhill 1986; Bailey et al. 2004); however, Fuller and Whelan (2018) provided historical evidence for its absence from the basin. University of Michigan voucher specimens are in Bailey et al. (2004) for two tributaries in southern Michigan. A single specimen was caught in the Canadian waters of western Lake Erie in 1978 by a commercial fisherman. This specimen was deposited in the Royal Ontario Museum collection (Crossman and Leach 1979). Despite the fact that Wydoski and Whitney (2003) say Flathead Catfish were in the lower Snake and Columbia rivers by the mid 1970s, neither the regional fishery biologist for that area, nor the warmwater fisheries manager for the state have ever seen or heard of one in the state (Chris Donnelly and Bruce Bolding, Washington Department of Fish and Wildlife, personal communication 1/6/2016, 1/7/2016). Although there is a supposed Washington State Record fish (22.8 lbs from the Snake River in 1981 (WDFW 2021), Bolding believes this was a misidentified Channel Catfish.

References: (click for full references)

Ashley, K. W., and B. Buff. 1986. Determination of current food habits of flathead catfish in the Cape Fear River. Final Report Submitted to the North Carolina Wildlife Resources Commission, Division of Boating and Inland Fisheries, Raleigh, NC. 19 pp.

Bailey, R.M., W.C. Latta, and G.R. Smith. 2004. An atlas of Michigan fishes with keys and illustrations for their identification. Miscellaneous Publications of the University of Michigan Museum of Zoology 192:1-215. http://deepblue.lib.umich.edu/handle/2027.42/56435.

Bart, H. L., M. S. Taylor, J. T. Harbaugh, J. W. Evans, S. L. Schleiger, and W. Clark. 1994. New distribution records of Gulf Slope drainage fishes in the Ocmulgee River system, Georgia. Southeastern Fishes Council Proceedings, No. 30:4--9.

Becker, G. C. 1983. Fishes of Wisconsin. University of Wisconsin Press, Madison, WI.

Bodine, K.A., R.A. Ott, D.L. Bennett, J.D. Norman, and J.W. Schlechte. 2021. Round 2: A 4-year follow-up evaluation of a Flathead Catfish population exposed to hand fishing. North American Journal of Fisheries Management 41:255–258. https://doi.org/10.1002/nafm.10476.

Bodine, K.A., J.W. Schlechte, R.A. Ott, D.L. Bennett, and J.D. Norman. 2016. Estimating exploitation and modeling the effects of hand fishing on a Flathead Catfish population in east Texas. North American Journal of Fisheries Management 36(6):1416–1424. https://doi.org/10.1080/02755947.2016.1209603.

Bond, C.E. 1994. Keys to Oregon freshwater fishes. Oregon State University Bookstores, Corvallis, OR.

Bonvechio, T.F., M.S. Allen, D. Gwinn and J.S. Mitchell. 2011. Impacts of electrofishing removals on the introduced Flathead Catfish population in the Satilla River, Georgia. Page 395–408 in Michaletz, P.H., and V.H. Travnichek, eds. Conservation, ecology, and management of catfish: the second international symposium. American Fisheries Society. Bethesda, MD.

Burgess, G. - Florida Museum of Natural History, Gainesville, FL.

Crossman, E.J., and J.H Leach. 1979. First Canadian record of a flathead catfish. Canadian Field-Naturalist 93:179-180.

Daugherty, D.J., and T.M. Sutton. 2005. Seasonal movement patterns, habitat use, and home range of Flathead Catfish in the Lower St. Joseph River, Michigan. North American Journal of Fisheries Management 25(1):256–269. https://doi.org/10.1577/m03-252.2.

Davis, R.A. 1985. Evaluation of flathead catfish as a predator in a Minnesota lake. No.. 384. Minnesota Department of Natural Resources, Division of Fish and Wildlife. http://www.nativefishlab.net/library/textpdf/13980.pdf.

Dill, W.A., and A.J. Cordone. 1997. History and status of introduced fishes in California, 1871-1996. Fish Bulletin 178. California Department of Fish and Game, Sacramento, CA. http://content.cdlib.org/view?docId=kt8p30069f&brand=calisphere.

Eggleton, M. A., and H. L. Schramm Jr. 2004. Feeding ecology and energetic relationships with habitat of Blue catfish, Ictalurus furcatus, and flathead Catfish, Pylodictis olivaris, in the lower Mississippi River, USA. Environmental biology of fishes 70:107-121.

Etnier, D.A., and W.C. Starnes. 1993. The fishes of Tennessee. University of Tennessee Press, Knoxville, TN.

Fuller, P.L., and G.E. Whelan. 2018. The flathead catfish invasion of the Great Lakes. Journal of Great Lakes Research 44(5):1081-1092.

Gilbert, C. - Florida Museum of Natural History, Gainesville, FL.

Gima, A. 2009. An evaluation of triploid Flathead Catfish. Unpublished M.S. thesis. Auburn University, Auburn, AL. https://etd.auburn.edu/xmlui/handle/10415/1460?show=full.

Guire, C.R., L.E. Nichols, and R.T. Rachels. 1984. Biological investigations of flathead catfish in the Cape Fear River. Proceedings of the Southeastern Association of Fish and Wildlife Agencies 35(1981):607--621.

Hedden, S.C., K.B. Gido, and J.E. Whitney. 2016. Introduced Flathead Catfish consumptive demand on native fishes of the Upper Gila River, New Mexico. North American Journal of Fisheries Management 36(1):55-61. https://doi.org/10.1080/02755947.2015.1111280.

Hubbs, C.L. and K.F. Lagler.  2004.  Fishes of the Great Lakes region.  Revised Edition.  University of Michigan, Ann Arbor, MI.

Hubert, W. 1994. Exotic fishes. Pages 158-174 in Parish, T.L., and S.H. Anderson, eds. Exotic species manual. Wyoming Game and Fish Department. Laramie, WY.

Hughes, R.M. and A.T. Herlihy. 2012. Patterns in catch per unit effort of native prey fish and alien piscivorous fish in 7 Pacific Northwest USA rivers. Fisheries 37(5):201-211.

Jackson, D.C. 1999. Flathead catfish: biology, fisheries, and management. American Fisheries Society Symposium 24:23-36.

Jenkins, R.E., and N.M. Burkhead. 1994. Freshwater Fishes of Virginia. American Fisheries Society, Bethesda, MD.

Kaar, C.R.J., C. Plikaitis, K.W. Germino, and A.K. Nakanishi. 2014. Catfish noodling forearm injury requiring urgent surgical treatment: A case report and review of the literature. Wilderness & Environmental Medicine 25:75–79. https://doi.org/10.1016/j.wem.2013.10.010.

Leis, E., R. Easy, L. MacLean, and D. Cone. 2018. Ligictaluridus michaelalicea n. sp (Monogenea: Dactylogyridae) from flathead catfish (Pylodictis olivaris) in the upper Mississippi River, including remarks on taxonomy influencing monogenean treatment regulation in the United States. Parasitology Research 117(3):825–830. https://doi.org/10.1007/s00436-018-5757-2.

Leis, E.M., T.G. Rosser, W.A. Baumgartner, and M.J. Griffin. 2017. Henneguya laseeae n. sp from flathead catfish (Pylodictis olivaris) in the upper Mississippi River. Parasitology Research 116(1):81–89. https://doi.org/10.1007/s00436-016-5264-2.

Lucchesi, D.O., M.D. Wagner, T.M. Stevens, and B.D.S. Graeb. 2017. Population dynamics of introduced flathead catfish in Lake Mitchell, South Dakota. Journal of Freshwater Ecology 32(1):314-327.

Marsh, P.C. and J.E. Brooks. 1989. Predation by Ictalurid catfishes as a deterrent to re-establishment of hatchery-reared razorback suckers. Southwestern Naturalist 34(2):188-195.

Mettee, M.F., P.E. O'Neil, and J.M. Pierson. 1996. Fishes of Alabama and the Mobile Basin. Oxmoor House, Inc, Birmingham, AL.

Michaletz, P.H. 2020. Bolstering piscivore abundance to restructure small impoundment fish communities. North American Journal of Fisheries Management 40(5):1276–1293. https://doi.org/10.1002/nafm.10494.

Minckley, W.L. 1973. Fishes of Arizona. Arizona Fish and Game Department, Phoenix, AZ.

Minckley, W. L., and James E. Deacon. 1959. New distributional records for three species of Kansas crayfish. Transactions of the Kansas Academy of Science 62(2):165.

Montague, G.F., and D.E. Shoup. 2021. Two decades of advancement in Flathead Catfish research. North American Journal of Fisheries Management 41(S1):S11–S26. https://doi.org/10.1002/nafm.10654S11.

Moody-Carpenter, C.J., G.G. Sass, L.D. Frankland, E.K. Bollinger, and R.E. Colombo. 2017. Demographics and interstate management implications for Flathead Catfish in the Lower Wabash River, Illinois and Indiana. North American Journal of Fisheries Management 37(6):1265–1273. https://doi.org/10.1080/02755947.2017.1376009.

Page, L.M., and B.M. Burr. 1991. A Field Guide to Freshwater Fishes - North America North of Mexico. Volume 42. Houghton Mifflin Company, Boston, MA.

Page, L.M., and B.M. Burr. 2011. A Field Guide to Freshwater Fishes of North America North of Mexico, Second Edition.  Houghton-Mifflin Harcourt. New York, NY.

Quinn, S.P. 1988. Stomach contents of flathead catfish in the Flint River, Georgia. Proceedings of the Annual Conference Southeastern Association of Fish and Wildlife Agencies 41:85-92.

Quinn, S.P. 2011. Human interactions with catfish. Page 800 in Michaletz, P.H., and V.H. Travnichek, eds. Conservation, ecology, and management of catfish: The second international symposium. American Fisheries Society. Bethesda, MD.

Schmitt, J.D., J.A. Emmel, A.J. Bunch, C.D. Hilling, and D.J. Orth. 2019. Feeding ecology and distribution of an invasive apex predator: Flathead Catfish in subestuaries of the Chesapeake Bay, Virginia. North American Journal of Fisheries Management 39(2):390–402. https://doi.org/10.1002/nafm.10279.

Simpson, J., and R. Wallace. 1978. Fishes of Idaho. University of Idaho Press, Moscow, ID.

Starnes, W.C., J. Odenkirk, and M.J. Ashton. 2011. Update and analysis of fish occurrences in the lower Potomac River drainage in the vicinity of Plummers Island, Maryland—Contribution XXXI to the natural history of Plummers Island, Maryland. Proceedings of the Biological Society of Washington 124(4):280-309.

Steffensen, K.D., S.A. Lundgren, and T.W. Huenemann. 2015. Documented predation of pallid sturgeon Scaphirhynchus albus (Forbes & Richardson, 1905) by flathead catfish Pylodictis olivaris (Rafinesque, 1818). Journal of Applied Ichthyology 31(5):843–845. https://doi.org/10.1111/jai.12831.

Stefferud, S. - U.S. Fish and Wildlife Service, Arizona Ecological Services Office, Phoenix, AZ.Underhill, J.C. 1986. The fish fauna of the Laurentian Great Lakes, the St. Lawrence lowlands, Newfoundland, and Labrador. Pages 105-136 in Hocutt, C.H., and E.O. Wiley, eds. The zoogeography of North American freshwater fishes. John Wiley and Sons. New York, NY.

Walker, P. - Maine Department of Inland Fisheries (formerly); Colorado Division of Wildlife, Brush, CO (currently).

Ward, D.L., and B.M. Vaage. 2019. What environmental conditions reduce predation vulnerability for juvenile Colorado River native fishes? Journal of Fish and Wildlife Management 10(1):196–205. https://doi.org/10.3996/042018-jfwm-031.

Washington Department of Fish and Wildlife (WDFW). 2021. Flathead catfish (Pylodictis olivaris). https://wdfw.wa.gov/species-habitats/species/pylodictis-olivaris. Accessed on 07/21/2016.

Williams, J. - U.S. Geological Survey (retired)

Winders, K.R., and J.A. McMullen. 2021. Size-specific exploitation of Flathead Catfish and Blue Catfish by recreational and commercial fishers in the Missouri and Mississippi Rivers, Missouri. North American Journal of Fisheries Management 41:247–254. https://doi.org/10.1002/nafm.10619.

Wydoski, R.S., and R.R. Whitney. 2003. Inland Fishes of Washington. Second Edition. American Fisheries Society, Bethesda, MD in association with University of Washington Press, Seattle, WA.

Other Resources:
Flathead catfish at the Fort Worth Zoo

Pennsylvania's flathead info - Pennsylvania Fish and Boat Commission

Pylodictis olivaris (Global Invasive Species Database)

Great Lakes Waterlife

US Fish and Wildlife Service Ecological Risk Screening Summary for Pylodictis olivaris

Author: Fuller, P., M. Neilson, R. Sturtevant, and A. Bartos

Peer Review Date: 3/24/2022

This information is preliminary or provisional and is subject to revision. It is being provided to meet the need for timely best science. The information has not received final approval by the U.S. Geological Survey (USGS) and is provided on the condition that neither the USGS nor the U.S. Government shall be held liable for any damages resulting from the authorized or unauthorized use of the information.