Noturus gyrinus

tadpole madtom



Type Locality

Wallkill River, New York (Mitchill 1817).


Etymology/Derivation of Scientific Name

Noturus, meaning “back tail,” in reference to the connection of the adipose fin and tail fin; gyrinus, Greek for “tadpole” (Pflieger 1997).



Silurus gyrinus Mitchill 1817:289.

Noturus gyrinus Evermann 1899:514; Cook 1959:141.

Schilbeodes gyrinus Evermann 1899:306; Hildebrand and Towers 1928:122.



Maximum size: 130 mm TL (Page and Burr 1991).


Life colors: Dark axial streak conspicuous; dorsal, anal, and caudal fins not dark-edged; lower lip and chin not heavily speckled with dark pigment (Hubbs et al. 1991).

Body uniformly brown (gray in preserved specimens) along back and sides, grading to white on belly. Bands of melanophores on upper and lower jaws, often a dark horizontal streak along the side. Nasal and maxillary barbels dusky; chin barbels vary from white to being lightly covered with melanophores. Pelvic and pectoral fins have scattered melanophores in adults, may be unpigmented in smaller fish. Dorsal and anal fins lightly covered with melanophores, with lighter margins. Adipose fin dark brown; caudal fin dark gray or black (Ross 2001). Holder and Ramsey (1972) reported an albino specimen.   


Counts: 6-7 gill rakers; 6-7 dorsal rays; 15-18 anal rays; 8 (7-9) pectoral rays; 9 (8-10) pelvic rays (Ross 2001).


Body shape:  Body heavy, round, and potbellied anteriorly (rarely elongate); strongly compressed posteriorly (Becker 1983).


Mouth position: Terminal; jaws nearly equal (Hubbs et al. 1991).


External morphology: Pectoral fin spine not serrated; adipose fin joined to the caudal fin or separated from it by not more than a shallow notch (Hubbs et al. 1991). Small eyes; anal fin moderately long, length of base going into SL 3.9-5.9 times; anal fin base becomes proportionately shorter with increasing body length (Ross 2001). Breeding males have enlarged muscles on top of the head, swollen lips, and enlarged genital papillae (Whiteside and Burr 1986).


Internal morphology: Ratio of digestive tract (DT) to total length (TL): DT 1.0-1.4 TL; intestine well differentiated; peritoneum colorless; pyloric caeca not present (Goldstein and Simon 1999). Numerous small, sharp, or peglike teeth in broad bands on upper and lower jaws; tooth patch on upper jaw without elongate, lateral backward extensions (Becker 1983).


Distribution (Native and Introduced)

U.S. distribution: Ranges widely east of the Rocky Mountains, except in upland streams draining the Appalachian mountain chain (Hubbs et al. 1991).


Texas distribution: Occurs widely throughout eastern Texas from the Red River to the Nueces Basin; also a report of this species from the Rio Grande in Webb County that may be a result of an introduction (Hubbs et al. 1991). Warren et al. (2000) list the following drainage units for distribution of Noturus gyrinus in the state: Red River (from the mouth upstream to and including the Kiamichi River), Sabine Lake (including minor coastal drainages west to Galveston Bay), Galveston Bay (including minor coastal drainages west to mouth of Brazos River), Brazos River, Colorado River, San Antonio Bay (including minor coastal drainages west of mouth of Colorado River to mouth of Nueces River), Nueces River.


Abundance/Conservation status (Federal, State, NGO)

Populations in the southern United Sates are currently secure (Warren et al. 2000). Often abundant where found (Rohde 1980).


Habitat Associations

Macrohabitat: Medium to large rivers, lakes, reservoirs, sloughs (Becker 1983).


Mesohabitat:  Typically inhabits quiet or slow-moving waters, especially over soft, muddy bottom with extensive vegetation (Rohde 1980). Tolerates at least a moderate amount of salinity, as Mansueti and Hardy (1967) reported species from the tidal portions of Virginia rivers. Holder and Ramsey (1972) collected specimens from dark, stained water with a pH of 4.5. According to Machniak and Gee (1975) individuals gulp air to inflate swimbladder, thereby gradually increasing buoyancy as water flow declines; volume of air in swimbladder may be reduced over several days, when flows increase, decreasing buoyancy and facilitating ability to maintain position in a stream.



Spawning season: In southern Mississippi, spawning takes place in April (Clark 1978). Spawning reported in Missouri and Mississippi during June or July (Rohde 1980). In more northern areas, spawning happens late spring through August (Case 1970; Mahon 1977; Whiteside and Burr 1986); June and July in Wisconsin (Becker 1983).


Spawning location: May use discarded glass or metal containers for nesting sites, or excavate one in gravel, usually under stones, boards or logs (Wang and Kernehan 1979); crayfish burrows, holes in mud, and under roots (Mansueti and Hardy 1967).


Reproductive strategy: Speleophils; hole nesters (Simon 1999). Little formal nest preparation; eggs deposited in clusters (Mansueti and Hardy 1967). According to Menzel and Raney (1973) females may mate several times during the breeding period. Wang and Kernehan (1979) reported that both parents help to guard and care for the eggs in the nesting site; fish move over egg mass in a shivering motion, anal fin in contact with eggs, or take a portion of egg mass into their mouth and spit it out. Taylor (1969) noted that egg-guarding individuals are in most cases male.


Fecundity: In lower Mississippi, clutches averaged 61 eggs, with 3.7 mm diameter (Clark 1978); in Illinois, clutches averaged 151 eggs, with 1.95 mm diameter (Whiteside and Burr 1986). In Delaware, number of fertilized eggs in a nest ranges from 93-150 (Wang and Kernehan 1979). In Mississippi, average clutch of 61 eggs, mature eggs averaging 3.7 mm diameter (Clark 1978); females in Illinois, of the same general size as specimens collected by Clark (1978), produced more and smaller eggs, average number of mature ova per female 151, with mean egg diameter of 1.95 mm; fertilized eggs demersal, adhesive, average 2.96 mm in diameter, and are light yellow-orange (Whiteside and Burr 1986).


Age/Size at maturation: 1 or 2 years (Hooper 1949; Rohde 1980; Whiteside and Burr 1986). Mature adults range from 50-76 mm

(Clark 1978).


Migration: Maximum reported movement was 2.1 km over a 13 week period in a

Canadian stream (Case 1970).


Growth and population structure: Specimens from a study in Illinois reached 40-52 mm SL in the first year, 49-64 mm SL after second, 54-71 mm SL after third, and 58-76 mm SL after fourth. Some populations show males with higher growth rates than females (Whiteside and Burr 1986). In Missouri streams, individuals attain length of about 30-56 mm by end of first summer (Pflieger 1997; Rohde 1980). By 15.5 mm TL, rays are developed in all fins except anterior region of caudal fin; at this size, fish closely resemble adults (Wang and Kernehan 1979).


Longevity: May live as long as 4 years, but most populations only have 10% older then two years (Hooper 1949; Rohde 1980; Whiteside and Burr 1986).


Food habits:  Goldstein and Simon (1999) list first and second level trophic classifications as invertivore/planktivore, and benthic/particulate feeder; list main food items as Cladocera, ostracods, Hyalella, chironomids, and other immature insects; Pearse (1918) reported diet contents from Wisconsin populations as 44% insects, 18.3% oligochaetes, 28.3% small crustaceans, 5.9% plants, 0.1% snails, 0.1% algae, 3% silt and debris. Case (1970) and Whiteside and Burr (1986) reported small crustaceans (amphipods and isopods), and small aquatic insect larvae (especially midges) as main food items. Fish smaller than 35 mm SL fed more on small crustaceans (copepods, cladocerans, ostracods); fish longer than 45 mm SL consumed large prey such as worms and grass shrimp (Whiteside and Burr 1986). Individuals leave cover at night and feed actively in the shallows (Becker 1983).


Phylogeny and morphologically similar fishes

Noturus gyrinus has a terminal mouth, unlike the freckled madtom (Noturus nocturnus), which has an inferior mouth (Ross 2001).


Host Records

This species is a host to the glochidia for the mussels Actinonaias carinata and Lampsilis radiata luteola (Becker 1983).


Commercial or Environmental Importance

One of the more venomous catfishes, having toxic sheath (apparently with neurotoxic and haemotoxic elements) covering dorsal and pectoral spines; threatened fish will arch back and erect spines, increasing its effective size to predator and exposing sharp spines; effect on humans has been compared to bee stings; toxin deters most predators (Case 1970; Birkhead 1972; Whiteside and Burr 1986).



Becker, G.C. 1983. Fishes of Wisconsin. University of Wisconsin Press, Madison. 1052 pp.

Birkhead, W.S. 1972. Toxicity of stings of ariid and ictalurid catfishes. Copeia 1972(4):790-807.

Case, B.E. 1970. An ecological study of the Tadpole Madtom Noturus gyrinus (Mitchell), with a special reference to movements and population fluctuations. Master's thesis. Univ. Manitoba.

Clark, K.E. 1978. Ecology and life history of the speckled madtom, Noturus leptacanthus (Ictaluridae). Master's thesis, Univ. S. Mississippi, Hattiesburg.

Cook. F.A. 1959. Freshwater fishes in Mississippi. Mississippi Fame and Fish Commission, Jackson. 239 pp.

Evermann, B. W. 1899. Report on investigations by the U.S. Fish Commission in Mississippi, Louisiana, and Texas, in 1897. Rept. U.S. Fish Comm. 1898:287-310.

Goldstein, R.M., and T.P. Simon. 1999. Toward a united definition of guild structure for feeding ecology of North American freshwater fishes. pp. 123-202 in T.P. Simon, editor. Assessing the sustainability and biological integrity of water resources using fish communities. CRC Press, Boca Raton, Florida. 671 pp.

Hildebrand S.F. and I.L. Towers. 1928. Annotated list of fishes collected in the vicinity of Greenwood, Mississippi, with descriptions of three new species. Bull. U.S. Bur. Fish. 43(2):105-136.

Holder, D.R., and J.S. Ramsey. 1972. A case of albinism in the tadpole madtom, Noturus gyrinus. Trans. Amer. Fish. Soc. 101(3):566-567.

Hooper, F.F. 1949. Age analysis of a population of the ameiurid fish, Schilbeodes mollis (Hermann). Copeia 1949(1):34-38.

Hubbs, C., R.J. Edwards, and G.P. Garrett.  1991.  An annotated checklist of the freshwater fishes of Texas, with keys to identification of species.  The Texas Journal of Science, Supplement, 43(4):1-56.

Machniak, K., and J.H. Gee. 1975. Adjustment of buoyancy by tadpole madtom, Noturus gyrinus, and black bullhead, Ictalurus melas, in response to change in water velocity. J. Fish. Res. Bd. Can. 32:303-307.

Mahon, R. 1977. Age and fecundity of the tadpole madtom, Noturus gyrinus, on Long Point, Lake Erie. Can. Field-Nat. 91(3):292-294.

Mansueti, A.J., and J.D. Hardy, Jr. 1967. Development of fishes of the Chesapeake Bay region. Port City Press, Baltimore, Maryland. 202 pp.

Menzel, B.W., and E.C. Raney. 1973. Hybrid madtom catfish, Noturus gyrinus X Noturus miurus, from Cayuga Lake, New York. Am. Midl. Nat. 90(1):165-176.

Mitchill, S.L.1817. Report on the ichthyology of the Wallkill, from the specimens of fishes presented to the society (Lyceum of Natural History) by Dr. B. Akerly. Amer. Monthly Mag. Crit. Rev. 1(4):289-290.

Page, L.M., and B.M. Burr.  1991.  A Field Guide to Freshwater Fishes of North America, north of Mexico.  Houghton Mifflin Company, Boston. 432 pp.

Pearse, A.S. 1918. The food of the shore fishes of certain Wisconsin lakes. Bull. U.S. Bur. Fish. 35:245-292.

Pflieger, W.L.  1997.  The Fishes of Missouri.  Missouri Department of Conservation, Jefferson City. 372 pp.

Rohde, F.C. 1980.  Noturus gyrinus (Mitchill), Tadpole madtom. pp. 459 in D. S. Lee et al., Atlas of North American Freshwater Fishes. N. C. State Mus. Nat. Hist., Raleigh, i-r+854 pp.

Ross, S.T. 2001. The Inland Fishes of Mississippi. University Press of Mississippi, Jackson. 624 pp.

Simon, T.P. 1999. Assessment of Balon’s reproductive guilds with application to Midwestern North American Freshwater Fishes, pp. 97-121. In: Simon, T.L. (ed.). Assessing the sustainability and biological integrity of water resources using fish communities. CRC Press. Boca Raton, Florida. 671 pp.

Taylor, W.R. 1969. A revision of the catfish genus Noturus Rafinesque with an analysis of higher groups in the Ictaluridae. Smithsonian Inst., U.S. Natl. Mus. Bull. 282. 315 pp.

Wang, J. C.S. and R.J. Kernehan. 1979. Fishes of the Delaware estuary. E. A. Communications, Ecological Analysts, Towson, Md.

Warren, M.L., Jr., B.M. Burr, S.J. Walsh, H.L. Bart, Jr., R.C. Cashner, D.A. Etnier, B.J. Freeman, B.R. Kuhajda, R.L. Mayden, H.W. Robison, S.T. Ross, and W.C. Starnes. 2000. Diversity, Distribution, and Conservation status of the native freshwater fishes of the southern United States. Fisheries 25(10):7-29.

Whiteside, L.A., and B.M. Burr. 1986. Aspects of the life history of the Tadpole Madtom Noturus gyrinus (Siluriformes: Ictaluridae), in southern Illinois. Ohio J. Sci. 86(4):153-160.