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Pylodictis olivaris (flathead catfish)
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Pictures
Top of page| Picture | Title | Caption | Copyright |  | Title | Adult |
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| Caption | Pylodictis olivaris (flathead catfish); adult. Captive specimen. |
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| Copyright | Released into the Public Domain by the U.S. Fish & Wildlife Service/National Digital Library - Original photograph by Brett Engbretson |
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| Adult | Pylodictis olivaris (flathead catfish); adult. Captive specimen. | Released into the Public Domain by the U.S. Fish & Wildlife Service/National Digital Library - Original photograph by Brett Engbretson |
 | Title | Adult |
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| Caption | Pylodictis olivaris (flathead catfish); adult. USA. |
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| Copyright | ©Todd Mathes/Department of Natural Resources/Bugwood.org - CC BY-NC 3.0 US |
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| Adult | Pylodictis olivaris (flathead catfish); adult. USA. | ©Todd Mathes/Department of Natural Resources/Bugwood.org - CC BY-NC 3.0 US |
 | Title | Adult |
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| Caption | Pylodictis olivaris (flathead catfish); adult. A 41lb (18.5kg) 'flathead', caught by hook and line. USA. |
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| Copyright | ©Todd Mathes/Department of Natural Resources/Bugwood.org - CC BY-NC 3.0 US |
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| Adult | Pylodictis olivaris (flathead catfish); adult. A 41lb (18.5kg) 'flathead', caught by hook and line. USA. | ©Todd Mathes/Department of Natural Resources/Bugwood.org - CC BY-NC 3.0 US |
Identity
Top of pagePreferred Scientific Name
- Pylodictis olivaris (Rafinesque, 1818)
Preferred Common Name
Other Scientific Names
- Pylodictus olivaris (Rafinesque, 1818)
- Silurus olivaris Rafinesque, 1818
International Common Names
- English: catfish
- Spanish: pintontle
Local Common Names
- Denmark: fladhovedet dværgmalle
- Finland: lättäpiikkimonni
Summary of Invasiveness
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P. olivaris, one of the largest members of the catfish family, predates heavily on native fishes and its introduction is recognized as the most biologically harmful of all fish introductions in North America (Fuller, 2000; ISSG, 2005). It is native to central parts of the continent but has been introduced to eastern and western areas. Its obligatory carnivorous food habits and ability to disperse rapidly with a rapid population growth rate have caused concern among ichthyologists and management agencies (Brown et al., 2005).
Taxonomic Tree
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- Domain: Eukaryota
- Kingdom: Metazoa
- Phylum: Chordata
- Subphylum: Vertebrata
- Class: Actinopterygii
- Order: Siluriformes
- Family: Ictaluridae
- Genus: Pylodictis
- Species: Pylodictis olivaris
Notes on Taxonomy and Nomenclature
Top of pageA monotypic genus (Glodek, 1980) Pylodictis is apparently unchanged since the mid-Miocene, forming the sister taxon to the blind, subterranean genus Satan. Pylodictus and Satan are the sister group to a clade containing Noturus (Lundberg, 1992; Ross, 2001).
Description
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P. olivaris has a slender, elongated body becoming moderately robust in adults (Ross, 2001). It has a depressed or flattened head with small eyes (Hubbs et al., 1991) and a terminal mouth (Goldstein and Simon, 1999) whose lower jaw projects forward beyond the upper jaw (Ross, 2001) except in juveniles (ISSG, 2005). This protruding lower jaw is an important characteristic when identifying the species as it distinguishes P. olivaris from other catfish and contributes to it being placed in a genus of its own (ISSG, 2005). In all individuals except large adults, the caudal fin of P. olivaris has a white tip on the upper lobe (Page and Sheehy, 2007).The body is yellow to dark purple-brown with black or brown mottling above and white to yellow below with white to yellow chin barbels and mottled fins (Page and Sheehy, 2007).
P. olivaris has 8-10 gill rakers, 6-7 dorsal rays, a short and rounded anal fin with 16-17 or 14-17 anal rays, 8-11 pectoral rays, and 9 pelvic rays (Ross, 2001). It has a premaxillary band of teeth on the upper jaw with a lateral backward extension on each side (Hubbs et al., 1991).
P. olivaris can grow up to over 45 kg in weight but most weigh one to seven kg (Page and Sheehy, 2007) and to a total length of 140 cm (Carlander, 1969) to 155 cm (Page and Sheehy, 2007). Maximum published weight is 55.8 kg (IGFA, 2001); maximum reported age is 20 years (FishBase, 2008).
Distribution
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The native range of P. olivaris includes a broad area west of the Appalachian Mountains encompassing large rivers of the Mississippi, Missouri, and Ohio basins; it extends as far north as North Dakota, as far west as New Mexico, and south to the Gulf including eastern Mexico (ISSG, 2005). The species has been introduced to eastern and western areas of the USA and to Ontario, Canada.
Distribution Table
Top of pageThe distribution in this summary table is based on all the information available. When several references are cited, they may give conflicting information on the status. Further details may be available for individual references in the Distribution Table Details section which can be selected by going to Generate Report.
History of Introduction and Spread
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P. olivaris has been introduced east of the Appalachian Mountains and into several western states (Fuller, 2000). It has become established in most waters where introduced (Fuller, 2008). For instance, it is widespread and reproducing in the lower Colorado River basin (Dill and Cordone, 1997). It has been reported from the San Pedro River, Arizona, and from the Suwannee River, Florida. Populations in the Apalachicola River, Florida, probably spread from introductions upstream in the Flint River, Georgia (Fuller, 2008). 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). It is not known how the species gained access to the upper reach of this river (Fuller, 2008). It also occurs in parts of Canada (NatureServes, 2002).
Introductions
Top of page| Introduced to | Introduced from | Year | Reason | Introduced by | Established in wild through | References | Notes |
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| Natural reproduction | Continuous restocking |
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| Ontario | | | | | Yes | | Coker et al., 2001 | |
Risk of Introduction
Top of pageP. olivaris can be spread by unintentional stock contamination of channel catfish shipments, but in most cases, it has been intentionally stocked (ISSG, 2005) and continues to spread if intentional stocking is continued.
Habitat
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P. olivaris is found in deep holes of medium and large-sized rivers (Glodek, 1980) and large streams (Minkley and Deacon, 1959), usually over hard bottoms. Individuals measuring 30 cm to 40 cm in length are associated with cover at intermediate depths in the stream, while larger individuals, more than 40 cm in length, almost invariably near more massive logs and drift, usually in or near deep holes in the stream bed (Minkley and Deacon, 1959).
Habitat List
Top of page| Category | Habitat | Presence | Status | | Freshwater |
| Rivers / streams | Principal habitat | Natural |
Biology and Ecology
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Genetics
The recorded haploid and diploid chromosomes number of P. olivaris in Ohio in the USA is 28 (n) and 56-56 (2n) (Arkhipchuk, 1999). The same haploid and diploid chromosome numbers of P. olivaris have been reported by LeGrande, (1981) and Klinkhardt et al. (1995) in unspecified locations. P. olivaris is reported to hybridize with the channel catfish (Ictalurus punctatus; Trautman, 1957). This species has been included in a DNA-barcoding study carried out by Hubert et al. (2008).
Reproductive Biology
Hatchery reared P. olivaris lay 3,000-5,000 gelatinous adhesive eggs (Henderson, 1965) with a diameter of 2.8 to 3.2 mm (Minckley and Deacon, 1959).
Eggs are gelatinous and adhesive (Breder and Rosen, 1966). In small hatchery-reared brood fish, spawns numbered from 3,000-5,000 eggs (Henderson, 1965). In Kansas, Minckley and Deacon, (1959) reported that females of 305-610 mm total length (TL) can produce from 6,900-11,300 eggs, averaging 2.8-3.2 mm diameter. Depending on size of females ranging from 1.05-11.66 kg, in an Oklahoma reservoir, 4,076-58,792 eggs were laid; ripe eggs averaged 3.7 mm diameter (Turner and Summerfelt, 1971). Snow (1959) reported egg mass weighing slightly less than 1,089 g (2.4 lb) which contained about 15,000 eggs. Giudice (1965) reported hatching of eggs in 6-7 days at 23.9-27.8°C. Snow, (1959) reported hatching in 9 days at 24-25.9°C, fry averaging 11 mm long.
P. olivaris males mature sexually at 3-4 years and females at 4-5 years (Minckley and Deacon, (1959). Carlander (1969) reported males usually maturing at 3-5 years old, after exceeding 38 cm TL, while females mature at 4-6 years old, and in excess of 46 cm TL.
Nutrition
Main food items of juveniles are microcrustaceans and insect larvae and main food items of adults are crayfishes, clams, and particularly fishes, including Carpiodes carpio, Notropis buchanani, N. lutrensis, N. stramineus, Semotilus atromaculatus, Ictalurus punctatus, Noturus nocturnus, P. olivaris, Lepomis megalotis, Percina phoxocephala, and Aplodinotus grunniens (Minckley and Deacon, 1959; Goldstein and Simon, 1999; Jackson, 1999).
Latitude/Altitude
Top of page| Latitude North (°N) | Latitude South (°S) | Altitude Lower (m) | Altitude Upper (m) | | 47-26 | 0 | 0 | 0 |
Water Tolerances
Top of page| Parameter | Minimum Value | Maximum Value | Typical Value | Status | Life Stage | Notes | | Salinity (part per thousand) | | | 0 | Optimum | | <10 tolerated |
| Water pH (pH) | 6 | 8 | | Optimum | | |
| Water temperature (ºC temperature) | 25 | 28 | | Optimum | | |
Means of Movement and Dispersal
Top of pageNatural Dispersal (Non-Biotic)
In Wisconsin, P. olivaris probably entered the Wolf and Fox drainages via the canal at Portage (Becker, 1983).
Accidental Introduction
P. olivaris can be spread by stock contamination of channel catfish shipments (Fuller, 2000). The presence of P. olivaris in eastern Pennsylvania is most likely due to stock contamination of channel catfish shipments (M Kaufman, personal communication as stated in Fuller, 2008). In Idaho P. olivaris were accidentally stocked instead of blue catfish (Simpson and Wallace, 1978).
Intentional Introduction
The flathead catfish has been intentionally stocked in most cases (Fuller, 2000). It is believed that P. olivaris were stocked by anglers circa 1950 in the vicinity of Potato Creek in Upson County, Georgia, with stock from the Tennessee drainage (Quinn, 1988).
The following account on the intentional introduction of P. olivaris is from Fuller (2008): “The species was 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). P. olivaris were stocked in Atlantic drainages (Savannah and Altamaha) in Georgia in the 1970s (Bart et al., 1994; C Jennings, personal communication [as stated in Fuller, 2008]). 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 P. olivaris 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 P. olivaris 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, as far as is known, P. olivaris was not taken into the lower Colorado River basin until after 1962.”
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 (Fuller, 2008).
Impact Summary
Top of page| Category | Impact | | Environment (generally) | Negative |
Environmental Impact
Top of pageImpact on Biodiversity
According to Fuller (2000), introductions of P. olivaris are probably the most biologically harmful of all fish introductions in North America. Many feeding studies have found that P. olivaris prey heavily on bullheads (Ameiurus spp.) (Fuller, 2000) and sunfish (Lepomis spp.) (Quinn, 1988; Fuller, 2000). According to Quinn (1988), introduced flatheads in the Flint River rely more on crayfish than any other catfish population described. One study also found that they reduced the number of common carp (Cyprinus carpio) in addition to bullheads (Ameiurus spp.), (Quinn, 1988). However, the introduced population in the Flint River system was also found that young-of-the-year P. olivaris fed on darters (Etheostoma spp.) clupeids, catostomids, ictalurids, and centrarchids (Quinn, 1988). A severe decline in native fish species, particularly native bullhead species, was observed in the Cape Fear River within 15 years of the first P. olivaris introduction (Guire et al., 1984; Jenkins and Burkhead, 1994).
Risk and Impact Factors
Top of pageImpact mechanisms
- Competition
- Hybridization
- Predation
- Rapid growth
Impact outcomes
- Altered trophic level
- Reduced native biodiversity
- Threat to/ loss of native species
Invasiveness
- Abundant in its native range
- Capable of securing and ingesting a wide range of food
- Fast growing
- Has a broad native range
- Has high genetic variability
- Has high reproductive potential
- Highly mobile locally
- Invasive in its native range
- Is a habitat generalist
- Long lived
- Proved invasive outside its native range
Similarities to Other Species/Conditions
Top of pageP. olivaris is unlikely to be mistaken for other catfishes, as it differs from the channel (Ictalurus punctatus) and blue (Ictalurus furcatus) catfishes in having a rounded caudal fin against forked caudal fin, and from the bullheads (Ameiurus) in having a greatly flattened head, posterior extensions of the premaxillary tooth patch, and a projecting lower jaw (Ross, 2001). Etnier and Starnes, (1993) noted juveniles might be mistaken for one of the madtom species (Noturus). However, the free posterior end of adipose fin of Pylodictis is apparent even in small sizes.
Prevention and Control
Top of pageControl Physical/mechanical control
According to Sea Grant (2003), a method of targeted removal of P. olivaris, establishing selective barriers, or disrupting the spawning of the exotic species without harming native species have been investigated in Pennsylvania's Delaware.
Chemical control
It has been discovered that P. olivaris exhibits a unique chemical sensitivity to the amino acid I-glutamine (Sea Grant, 2003). After testing electrical responses of taste buds (or olfactory neurons) located on the skin and whiskers of the fish to 10 amino acids, it was determined that P. olivaris, unlike native channel catfish (Ictalurus punctatus), was most sensitive to I-glutamine.
References
Top of pageArkhipchuk VV, 1999. Chromosome database. Database of Dr. Victor Arkhipchuk.
Ashley KW, Buff B, 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.
Bart HL, Taylor MS, Harbaugh JT, Evans JW, Schleiger SL, Clark W, 1994. New distribution records of Gulf Slope drainage fishes in the Ocmulgee River system, Georgia. Southeastern Fishes Council Proceedings., 4-9.
Becker GC, 1983. Fishes of Wisconsin. Madison, WI, USA: University of Wisconsin Press, xii + 1052 pp.
Breder Jr CM, Rosen DE, 1966. Modes of Reproduction in Fishes. Jersey City, New Jersey, : T.F.H. Publications, 941 pp.
Brown JJ, Perillo J, Kwak TJ, Horwitz RJ, 2005. Implications of Pylodictis olivaris (flathead catfish) introduction into the Delaware and Susquehanna drainages. Northeastern Naturalist, 12(4):473-484.
Carlander KD, 1969. Handbook of freshwater fishery biology. Volume 1. Iowa State Univ. Press, Ames, vi+752 pp.
Coad BW, Waszczuk H, Labignan I, 1995. Encyclopedia of Canadian fishes. Canadian Museum of Nature and Canadian Sportfishing Productions Inc. Singapore.
Coker GA, Portt CB, Minns CK, 2001. Morphological and ecological characteristics of Canadian freshwater fishes. Can. Manuscr. Rep. Fish. Aquat. Sci, No. 2554:89 pp.
Dill WA, Cordone AJ, 1997. History and status of introduced fishes in California, 1871-1996. Fish Bulletin, 178:1-414.
Etnier DA, Starnes WC, 1993. The Fishes of Tennessee. Knoxville, USA: University of Tennessee Press, 681 pp.
Froese R, Pauly D, 2008. FishBase. http://www.fishbase.org
Fuller P, 2000. Pylodictis olivaris. Nonindigenous Aquatic Species Database. Gainesville, FL, . http://nas.er.usgs.gov/queries/FactSheet.asp?speciesID=750
Fuller P, 2008. Pylodictis olivaris. USGS Nonindigenous Aquatic Species Database,. Gainesville, FL, . http://nas.er.usgs.gov/queries/FactSheet.asp?speciesID=750
Giudice JJ, 1965. Investigations on the propagation and survival of flathead catfish in troughs. Proc. Southeast. Assoc. Game Fish Commnrs, 17:178-180.
Glodek GS, 1980. Pylodictis olivaris (Rafinesque) Flathead catfish. In: Atlas of North American Freshwater fishes [ed. by Lee , DS]: N. C. State Mus. Nat. Hist., Raleigh, 472.
Goldstein RM, Simon TP, 1999. Toward a united definition of guild structure for feeding ecology of North American freshwater fishes. In: Assessing the sustainability and biological integrity of water resources using fish communities [ed. by Simon, TP] Boca Raton, Florida: CRC Press, 123-202.
Guire CR, Nichols LE, Rachels RT, 1984. Biological investigations of flathead catfish in the Cape Fear River. Proceedings of the Southeastern Association of Fish and Wildlife Agencies, 35,:607-621.
Henderson H, 1965. Observation on the propagation of flathead catfish in the San Marcos State fish hatchery, Texas. Proc. Southeast. Assoc. Game Fish Commnrs, 17:173-177.
Hubbs C, Edwards RJ, Garrett GP, 1991. An annotated checklist to the freshwater fishes of Texas, with keys to identification of species. The Texas Journal of Science, Supplement, 43(4):1-56.
Hubert N, Hanner R, Holm E, Mandrak NE, Taylor E, Burridge M, Watkinson D, Dumont P, Curry A, Bentzen P, Zhang J, April J, Bernatchez L, 2008. Identifying Canadian freshwater fishes through DNA barcodes. Plos One, 3(6):e2490.
IGFA, 2001. 2001 Database of IGFA angling records until 2001. Fort Lauderdale, USA: IGFA.
ISSG, 2005. Pylodictis olivaris. Global Invasive Species Database (online). http://www.issg.org/database/species/ecology.asp?si=331&fr=1&sts=sss
Jackson DC, 1999. Flathead catfish: Biology, fisheries and management. In: Catfish 2000: Proceedings of the International Ictalurid Symposium. American Fisheries Society Symposium 24, [ed. by Irwin ER, Hubert WA, Rabeni CF, Schramm Jr HL, Coon T] Bethesda, M.D.,, : American Fisheries Society,, pp 23-35.
Jenkins RE, Burkhead NM, 1994. Freshwater fishes of Virginia. Bethesda, MD, USA: American Fisheries Society.
Klinkhardt M, Tesche M, Greven H, 1995. Database of fish chromosomes. Germany: Westarp Wissenschaften.
LeGrande WH, 1981. Chromosomal evolution in North American catfishes (Siluriformes: Ictaluridae) with particular emphasis on the madtoms, Noturus. Copeia, 1:33-52.
Lundberg JG, 1992. The phylogeny of ictalurid catfishes: a synthesis of recent work. In: Systematics, Historical Ecology, and North American freshwater fishes [ed. by Mayden RL] Stanford, CA,, : Stanford Univ. Press,, 392-420.
Minckley WL, 1973. Fishes of Arizona. Arizona Fish and Game Department. Phoenix, AZ, USA: Sims Printing Company, Inc.
Minckley WL, Deacon JE, 1959. Biology of the flathead catfish in Kansas. Transactions of the American Fisheries Society, 88:344-355.
NatureServe, 2002. Pylodictis olivaris. NatureServe Explorer. http://www.natureserve.org/explorer
Page L, Sheehy G, 2007. Pylodictis. Pylodictis olivaris (Rafinesque 1818). Flathead Catfish. http://tolweb.org/Pylodictis_olivaris/69915/2007.05.23
Page LM, Burr BM, 1991. A field guide to freshwater fishes of North America north of Mexico. Boston, USA: Houghton Mifflin Company, 432 pp.
Quinn SP, 1988. Stomach contents of flathead catfish in the Flint River, Georgia. In: Proceedings of the 41st Annual Conference of Southeastern Association of Fish and Wildlife Agencies, 85-92.
Ross ST, 2001. The Inland Fishes of Mississippi. University Press of Mississippi, Jackson, 624 pp.
Sea Grant, 2003. Could Flathead Catfish's Unique Chemical Sensitivity Be Used to Repel Invasive Exotic? Sea Grant (online). http://www.pserie.psu.edu/seagrant/communication/news/winter03.html
Simpson J, Wallace R, 1978. Fishes of Idaho. Moscow, ID, : University of Idaho Press,.
Sublette JE, Hatch MD, Sublette M, 1990. The fishes of New Mexico. Albuquerque, New Mexico: University New Mexico Press, 393 pp.
Turner PR, Summerfelt RC, 1971. Reproductive biology of the flathead catfish, Pylodictus olivais (Rafinesque), in a turbid Oklahoma Reservoir. Reservoir Fisheries and Limnology Am. Fish. Soc. Spec. Pub [ed. by Hall GE, ]., 107-119.
Contributors
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18/06/08 Original text by:
Sunil Siriwardena, Institute of Aquaculture, University of Stirling, Stirling, FK9 4LA, UK
Distribution Maps
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- = Present, no further details
- = Evidence of pathogen
- = Widespread
- = Last reported
- = Localised
- = Presence unconfirmed
- = Confined and subject to quarantine
- = See regional map for distribution within the country
- = Occasional or few reports