Pylodictis olivarisCatfish

Geographic Range

Flathead catfish are native to rivers and lakes in the lower Great Lakes and Mississippi River basin. They are found in appropriate habitat in Texas, Louisiana, Arkansas, Oklahoma, Arkansas, Missouri, Kansas, much of Nebraska, South Dakota, North Dakota, Iowa, Minnesota, Illinois, Indiana, Ohio, Kentucky, western Virginia, Tennessee, Alabama, and as far south as Mexico. (Fuller and Neilson, 2001; Page and Burr, 2011)

This species has been introduced farther east and west of its native range, to parts of Washington, Oregon, California, Arizona, New Mexico, Wyoming, Colorado, Georgia, South Carolina, North Carolina, Virginia, and Pennsylvania. (Fuller and Neilson, 2001; Page and Burr, 2011)


Flathead catfish inhabit rivers, lakes, and reservoirs with slow currents. Younger individuals prefer shallower water. Older and larger flathead catfish stay in deeper waters during the daylight hours (typical depth 3-6 m), moving into shallower water at night. They prefer to remain near or under cover, including fallen trees, logs, brush piles, and river banks. A log that is 5 m long is large enough to provide sufficient cover for one large adult flathead catfish. These catfish are generally found in waters from 21.7 to 30°C. (Brown, et al., 2005; Lee and Terrell, 1987; Malindzak, 2006; Minckley and Deacon, 1959; Page and Burr, 2011)

  • Aquatic Biomes
  • lakes and ponds
  • rivers and streams
  • Range depth
    3 to 6 m
    9.84 to 19.69 ft

Physical Description

This is a large-bodied species that can attain sizes of over one meter in length and 56 kg in weight. Flathead catfish are also called mud catfish, because of their yellow to purple-brown dorsal coloration. The belly is pale white to yellow. Not surprisingly, their head is wider and flatter than that of other North American catfishes. The lower jaw protrudes farther out than the upper jaw, with the mouth having a wide oval shape. The caudal fin has rounded to slightly notched posterior margin, and a white tip on the upper lobe (except in large adults), which can be used to distinguish this species from other members of the family Ictaluridae. Flathead catfish have both pectoral and dorsal-fin spines. The anal fin is short and rounded in profile, and contains 14-17 elements. There is no externally discernible physical difference between males and females. (Brown, et al., 2005; Kwak, et al., 2006; Lee and Terrell, 1987; Page and Burr, 2011)

  • Sexual Dimorphism
  • sexes alike
  • Range mass
    0.5 to 56.7 kg
    1.10 to 124.89 lb
  • Average mass
    20.4 kg
    44.93 lb
  • Range length
    38.1 to 114.3 cm
    15.00 to 45.00 in


Fertilized eggs hatch in 6 to 9 days, depending on temperature, with larvae being from 11 to 14.8 mm in total length. A large, spherical yolk sac is present, and extends from the rear edge of the eye to the pelvic fin buds. The gills, mouth, and digestive system are all functional at this point, although the yolk sac is the primary source of nutrition until it is completely absorbed (at a total length of approximately 17.6 mm). Newly hatched individuals have rudiments of the future spines and rayed elements of the dorsal, pectoral, and caudal fins. All fins will generally attain full development by the time the yolk sac is absorbed. Like other ictalurid species, flathead catfish grow continuously, gradually attaining adult body proportions and coloration patterns. Adults can range from 58 mm to more than 1000 mm in length, depending on age, and there have been reports of individuals of over 1500 mm. They do not normally exceed 1000 mm until they reach 10 years of age. (Lee and Terrell, 1987; Simon and Wallus, 2003)


Flathead catfish mating systems have not been observed in the wild, but mating in captivity has been observed and documented. The male moved over and around the female, rubbing her with his belly and, apparently, his barbels. He then stopped swimming, with his tail surrounding the female's head, while making strong, quivering movements. This behavior was repeated periodically until the female was ready to spawn, 2 weeks later. At that time, the female deposited eggs in a depression that had been made in the aquarium gravel, which were then fertilized by the male. Total spawning time was approximately 4 hours, after which the female was removed and the male began ferociously defending the eggs, even from the female that had layed them. (Simon and Wallus, 2003)

Age at sexual maturity appears to be regionally dependent, and can range from 3 to 5 years in males and 3 to 7 years in females. Spawning occurs in early to late summer, when the water temperature is 23.8 to 29°C, with eggs hatching 6 to 9 days post-fertilization. Nests are constructed under cover, including logs, stumps, brush piles, and rock outcroppings. The number of eggs produced by a female is positively correlated with her body size, and a single nest can contain up to 100,000 eggs. The eggs are adhesive, and are expelled in masses of 30 to 50 individual eggs. (Lee and Terrell, 1987; Simon and Wallus, 2003)

  • Breeding interval
    Flathead catfish breed once yearly
  • Breeding season
    Spawning occurs in June and July.
  • Range number of offspring
    100,000 (high)
  • Range time to hatching
    6 to 9 days
  • Range age at sexual or reproductive maturity (female)
    3 to 7 years
  • Average age at sexual or reproductive maturity (female)
    4 years
  • Range age at sexual or reproductive maturity (male)
    3 to 5 years

Males guard the eggs until they hatch, after which he will continue to protect the newborn fish for several days. (Lee and Terrell, 1987; Simon and Wallus, 2003)

  • Parental Investment
  • pre-fertilization
    • provisioning
    • protecting
      • female
  • pre-hatching/birth
    • provisioning
      • female
    • protecting
      • male
  • pre-independence
    • protecting
      • male


Flathead catfish can live up to 28 years, although the typical lifespan is 5 to 22 years, based on pectoral spine and otolith age estimates. Due to the large size of adults, this species is not commonly kept in captivity. (Kwak, et al., 2006)

  • Range lifespan
    Status: wild
    28 (high) years
  • Typical lifespan
    Status: wild
    5 to 22 years


Flathead catfish occupy deeper parts of rivers and lakes. They are ambush predators, waiting in and under cover for their prey to cross their path. This species is primarily nocturnal, but is sometimes active during the day as well. Flathead catfish are mainly piscivorous, and are infamous for eating other game fish in the non-native areas where they have been introduced. They become mostly inactive when water temperatures drop below 10°C. (Brown, et al., 2005; Daugherty and Sutton, 2005; Eggleton and Schramm, 2004; Lee and Terrell, 1987; Vokoun and Rabeni, 2006)

  • Range territory size
    0 to 3601 m^2
  • Average territory size
    1135 m^2

Home Range

Individual home ranges vary throughout the year. In a study in a southwest Michigan river, seasonal differences in movement were pronounced. During the spring, which is the most active time of the year, the average home range was 1,513 m of stream. In the summer months, the catfish being studied moved an average of 596 m upstream or downstream. During the fall, the average home range was 1,250 m of stream. Since these catfish are inactive during the winter, their home range at that time is presumably much reduced, although it was not explicitly measured. (Daugherty and Sutton, 2005)

Communication and Perception

The captive spawning activity discussed above indicates that tactile, and possibly chemical cues are used in communication between flathead catfish. This species is able to sense its environment using its eyes, mechanosensory lateral line, and the taste buds covering its body, which are concentrated on the barbels. Flathead catfish (like all otophysan fishes) have an improved sense of hearing due to the presence of their Weberian apparatus, which connects the swim bladder (which serves as a resonance chamber) to the inner ear. (Hoagland, 1933; Kanwal and Caprio, 1987; Nelson, 2006; Pohlmann, et al., 2004)

Food Habits

Flathead catfish are carnivores that prey on many different types of animals, depending on size. They are known to eat crayfish, gizzard shad (Dorosoma cepedianum), insects and larvae, channel catfish (Ictalurus punctatus), drum (Aplodinotus grunniens), other flatheads (Pylodictis olivaris), green sunfish (Lepomis cyanellus) and carp. Insect larvae are the major prey type until an individual reaches approximately 100 mm in total length, at which point the diet expands to include crayfish and small fishes. Individuals above 250 mm in length feed almost exclusively on other fishes. (Brown, et al., 2005; Layher and Boles, 1980; Simon and Wallus, 2003)

  • Animal Foods
  • fish
  • insects
  • aquatic crustaceans


Flathead catfish have no known predators other than members of their own species and humans who fish for them. Although, when they are larvae and younger, smaller fish, they are likely to be prey to other fish, wading birds, such as herons, and other medium-sized predators that forage in rivers and streams. (Brown, et al., 2005)

  • Anti-predator Adaptations
  • cryptic
  • Known Predators
    • humans (Homo sapiens)
    • flathead catfish (Pylodictis olivaris)

Ecosystem Roles

Flathead catfish serve as one of the top predators of other fishes in the areas they inhabit, and thus represent a potentially harmful invasive organism outside of their native range. This species has been observed to host over 25 different parasitic species, including several types of platyhelminth worms, nematodes, spiny-headed worms, leeches, copepods, water lice, and freshwater mussel larvae. (Brown, et al., 2005; Causey, 1957; Hoffman, 1999; Poly, 1997; Robinson and Jahn, 1980)

Commensal/Parasitic Species
  • Ambiphrya ictaluri (Order Ciliata, Phylum Ciliophora)
  • Ligictaluridus floridanus (Class Monogenea, Phylum Platyhelminthes)
  • Ligictaluridus mirabilis (Class Monogenea, Phylum Platyhelminthes)
  • Allochanthochasmus artus (Class Trematoda, Phylum Platyhelminthes)
  • Alloglossidium corti (Class Trematoda, Phylum Platyhelminthes)
  • Caecincola parvulus (Class Trematoda, Phylum Platyhelminthes)
  • Crepidostomum cornutum (Class Trematoda, Phylum Platyhelminthes)
  • Phyllodistomum lacustri (Class Trematoda, Phylum Platyhelminthes)
  • Phyllodistomum staffordi (Class Trematoda, Phylum Platyhelminthes)
  • Podocotyle boleosomi (Class Trematoda, Phylum Platyhelminthes)
  • Corallobothrium fimbriatum (Class Cestoda, Phylum Platyhelminthes))
  • Corallobothrium giganteum (Class Cestoda, Phylum Platyhelminthes))
  • Corallobothrium tva (Class Cestoda, Phylum Platyhelminthes))
  • Marsipometra sp. (Class Cestoda, Phylum Platyhelminthes)
  • Proteocephalus ambloplitis (Class Cestoda, Phylum Platyhelminthes)
  • Proteocephalus macrocephalus (Class Cestoda, Phylum Platyhelminthes)
  • Camallanus oxycephalus (Class Secernentea, Phylum Nematoda)
  • Contracaecum spiculigerum (Class Secernentea, Phylum Nematoda)
  • Dacnitoides sp. (Class Secernentea, Phylum Nematoda)
  • Leptorhynchoides thecatus (Class Metacanthocephala, Phylum Acanthocephala)
  • Chloromyxum opladeli (Class Myxosporea, Phylum Cnidaria)
  • Cystobranchus verrilli (Subclass Hirudinea, Phylum Annelida)
  • larvae of unionid mollusks (Unionidae)
  • Actheres pimelodi (Subclass Copepoda, Subphylum Crustacea)
  • Ergasilus versicolor (Subclass Copepoda, Subphylum Crustacea)
  • Argulus appendiculosus (Subclass Branchiura, Subphylum Crustacea)
  • Argulus flavescens (Subclass Branchiura, Subphylum Crustacea)

Economic Importance for Humans: Positive

Flathead catfish are prized by anglers, and may therefore have positive impacts in terms of ecotourism. (Page and Burr, 2011)

Economic Importance for Humans: Negative

There are no known negative economic effects of flathead catfish on humans. The fin spines of smaller specimens are quite sharp, and may injure unwary fishermen. (Brown, et al., 2005)

  • Negative Impacts
  • injures humans

Conservation Status

There are no current conservation efforts to protect flathead catfish, as they are not considered vulnerable or threatened in any portion of their geographical range.


Nicholas Brodd (author), Radford University, Karen Powers (editor), Radford University, Kiersten Newtoff (editor), Radford University, Melissa Whistleman (editor), Radford University, Jeremy Wright (editor), University of Michigan-Ann Arbor.



living in the Nearctic biogeographic province, the northern part of the New World. This includes Greenland, the Canadian Arctic islands, and all of the North American as far south as the highlands of central Mexico.

World Map


uses sound to communicate

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.


an animal that mainly eats meat


uses smells or other chemicals to communicate


having markings, coloration, shapes, or other features that cause an animal to be camouflaged in its natural environment; being difficult to see or otherwise detect.


humans benefit economically by promoting tourism that focuses on the appreciation of natural areas or animals. Ecotourism implies that there are existing programs that profit from the appreciation of natural areas or animals.


animals which must use heat acquired from the environment and behavioral adaptations to regulate body temperature

external fertilization

fertilization takes place outside the female's body


union of egg and spermatozoan


mainly lives in water that is not salty.


having a body temperature that fluctuates with that of the immediate environment; having no mechanism or a poorly developed mechanism for regulating internal body temperature.


the state that some animals enter during winter in which normal physiological processes are significantly reduced, thus lowering the animal's energy requirements. The act or condition of passing winter in a torpid or resting state, typically involving the abandonment of homoiothermy in mammals.

indeterminate growth

Animals with indeterminate growth continue to grow throughout their lives.


An animal that eats mainly insects or spiders.


referring to animal species that have been transported to and established populations in regions outside of their natural range, usually through human action.


offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).


Having one mate at a time.


having the capacity to move from one place to another.


specialized for swimming

native range

the area in which the animal is naturally found, the region in which it is endemic.


active during the night


reproduction in which eggs are released by the female; development of offspring occurs outside the mother's body.


an animal that mainly eats fish

seasonal breeding

breeding is confined to a particular season


reproduction that includes combining the genetic contribution of two individuals, a male and a female


lives alone


uses touch to communicate


that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).


movements of a hard surface that are produced by animals as signals to others


uses sight to communicate


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Bringolf, R., T. Kwak, G. Cope, M. Larimore. 2005. Salinity tolerance of flathead catfish: Implications for dispersal of introduced populations. Transactions of the American Fisheries Society, 134/4: 927-936.

Brown, J., J. Perillo, T. Kwak, R. Horwitz. 2005. Implications of Pylodictis olivaris (flathead catfish) introduction into the Delaware and Susquehanna drainages. Northeastern Naturalist, 12/4: 473-484.

Causey, D. 1957. Parasitic copepoda from Louisiana fresh water fish. American Midland Naturalist, 58/2: 378-382.

Daugherty, D., T. Sutton. 2005. Seaonal movement patterns, habit use, and home range of flathead catfish in the lower St. Joseph River, Michigan. North American Journal of Fisheries Management, 25: 256-269.

Eggleton, M., H. Schramm. 2004. Feeding ecology and energetic relationships with habitat of blue catfish, Ictalurus furcatus, and flathead catfish, Pylodictis olivaris, in the lower Mississippi River, U.S.A. Environmental Biology of Fishes, 70/2: 107-121.

Fuller, P., M. Neilson. 2001. "Pylodictis olivaris" (On-line). USGS nonindigenous aquatic species database. Accessed February 09, 2012 at

Hoagland, H. 1933. Specific nerve impulses from gustatory and tackle receptors in catfish. The Journal of General Physiology, 16/4: 685-693.

Hoffman, G. 1999. Parasites of North American Freshwater Fishes. Ithaca, NY: Comstock Publishing Associates (Cornell University Press).

Kanwal, J., J. Caprio. 1987. Overlapping taste and tactile maps of the oropharynx in the vagal lobe of the channel catfish, Ictalurus punctatus. Journal of neurobiology, 19/3: 211-222.

Kwak, T., W. Pine III, S. Waters. 2006. Age, growth, and mortality of introduced flathead catfish in Atlantic rivers and a review of other populations. North American Journal of Fisheries Management, 26: 73-87.

Layher, W., R. Boles. 1980. Food habits of the flathead catfish, Pylodictis olivaris (Rafinesque), in relation to length and season in a large Kansas reservoir. Transactions of the Kansas Academy of Sciences, 83/4: 200-214.

Lee, L., J. Terrell. 1987. Habitat suitability index models: flathead catfish. Fort Collins, CO: U.S. Fish and Wildlife Service.

Malindzak, E. 2006. "Behavior and habitat use of introduced flathead catfish in a North Carolina piedmont river" (On-line). Thesis for North Caroline State University. Accessed February 08, 2012 at

Minckley, W., J. Deacon. 1959. Biology of the flathead catfish in Kansas. Transactons of the American Fisheries Society, 88/4: 344-355.

Nelson, J. 2006. Fishes of the World, Fourth Edition. Hoboken, NJ: John Wiley & Sons, Inc..

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

Pohlmann, K., J. Atema, T. Breithaupt. 2004. The importance of the lateral line in nocturnal predation of piscivorous catfish. Journal of Experimental Biology, 207: 2971-2978.

Poly, W. 1997. Host and Locality Records of the Fish Ectoparasite, Argulus (Branchiura), from Ohio (U.S.A.). Crustaceana, 70/8: 867-874.

Robinson, G., L. Jahn. 1980. Some observations of fish parasites in pool 20, Mississippi River. Transactions of the American Microscopical Society, 99/2: 206-212.

Simon, T., R. Wallus. 2003. Reproductive Biology and Early Life History of Fishes in the Ohio River Drainage, Volume 3, Ictaluridae-Catfish and Madtoms. Boca Raton, FL: CRC Press LLC.

Vokoun, J., C. Rabeni. 2006. Summer diel activity and movement paths of flathead catfish (Pylodictis olivaris) in two Missouri streams. American Midland Naturalist, 155/1: 113-122.