Pylodictis olivaris
(Flathead Catfish)
Fishes
Native Transplant |
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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).
Nonindigenous Occurrences:
Table 1. States with nonindigenous occurrences, the earliest and latest observations in each state, and the tally and names of HUCs with observations†. Names and dates are hyperlinked to their relevant specimen records. The list of references for all nonindigenous occurrences of Pylodictis olivaris are found here.
Table last updated 12/12/2025
† Populations may not be currently present.
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 and Lagler 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: Summary of species impacts derived from literature review. Click on an icon to find out more...
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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).
