Picture by Chad Thomas, Texas State University-San Marcos



Aplodinotus grunniens

freshwater drum



Type Locality

Ohio River (Rafinesque 1819).


Etymology/Derivation of Scientific Name:

Aplodinotus, Greek, meaning “single back,” in reference to the dorsal fin; grunniens, Latin, meaning “grunting,” in reference to sounds production in this species (Pflieger 1997) .



Aplodinotus grunniens Rafinesque 1819:418; Hildebrand and Towers 1928:135; Cook 1959:211.

Amblodon Wailes 1854:333.

Haploidontus grunniens Hay 1883:64.



Maximum size: 696 mm TL (Wrenn 1969).


Coloration:  Monotone silver; Dorsal and caudal fins outlined with black pigments.


Pharyngeal teeth count:  NA


Counts: Fewer than 60 lateral line scales (Hubbs et al. 1991); 10 dorsal spines; 30 dorsal rays; 20-24 gill rakers (Knapp 1953); 2 anal spines; 6-7 anal rays; 15-16 pectoral rays; 1 pelvic spine; 5 pelvic rays (Ross 2001).


Body shape: Strongly arched body, laterally compressed.


Mouth position: Subterminal (Goldstein and Simon 1999).


External morphology: Shortest dorsal spine <1/2 of longest dorsal spine, forming a distinct, deep notch between spiny dorsal fin and soft dorsal fin rays.  Anteriorly-arched lateral line extends into caudal fin.


Distribution (Native and Introduced)

U.S. distribution:  Central North America from Canada to Central America (Hubbs et al. 1991). Apparently has greatest latitudinal range of any North American freshwater fish (Fremling 1980).


Texas distribution: Widely occurring except in the Panhandle region (Hubbs et al. 1991). Warren et al. (2000) listed the following drainage units for distribution of Aplodinotus grunniens 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):

Currently stable in southern US (Warren et al. 2000). Edwards and Contreras-Balderas (1991) reported a general decline of this species in the lower Rio Grande in the last 100-year period.


Habitat Associations

Macrohabitat:  Turbid to clear lakes and rivers, but does occur in a wide variety of habitats (Fremling 1980).


Mesohabitat: Benthic habitats of large, shallow bodies of water (to 40-60 feet; Scott and Crossman 1973). More commonly associated with large woody debris than open areas in Kansas reservoir (Willis and Jones 1986). In large rivers, fish may move distances of at least 161 km (Funk 1955). In Lake Texoma (Oklahoma-Texas), larvae responded to increased turbidity by moving up near the surface, instead of remaining in deep water during daylight hours, as typical (Matthews 1984). Gido and Matthews (2000) reported marked seasonal abundance patterns for large fish in Lake Texoma (Oklahoma-Texas), with peak in abundance during warm seasons; the abundance of juvenile (< 200 mm SL) fish increased during summer; also, large fish increased in relative abundance during increased periods of reservoir volume. Riggs and Bonn (1959) noted that the species was fairly common in most deeper parts of Lake Texoma (Oklahoma-Texas), and was abundant in the tail waters. Li (2003) reported that the species was commonly collected in deepwater sites of the lower Brazos River, Texas, during summer and winter seasons; was positively associated with conductivity and strongly associated with summer samples. After reaching 25 mm in length, fish are found on or near bottom (Priegel 1967b). Individuals have been observed to become distressed when water temperatures exceed 25.6°C, and when dissolved oxygen concentrations remain low over an extended period (Priegel 1967b).



Spawning season: In May and June, usually at water temperatures between 18-26°C (Wrenn 1969; Swedberg and Walburg 1970; Fremling 1980).


Spawning location:  Open water.  In the Upper Mississippi River, eggs and larvae were abundant in the main channel collections (Holland 1986).


Reproductive strategy:  Nonguarders; open substratum spawners; pelagophils – characterized by numerous buoyant eggs (Simon 1999).  Eggs and sperm released in the water column; eggs are buoyant, larvae are planktonic (Daiber 1953).  Males “drum” communicate to form spawning aggregates by vibrating specialized muscles against gas bladder (Fremling 1980); only sexually mature males possess this structure, which may be fully developed by the third year of life (Priegel 1967b).


Fecundity: 600,000 eggs for large females (3.5 kg; Wrenn 1969; Fremling 1980).  Number of vitellogenic oocytes ranged from 34,000 to 66,500, in 6-9 year-old fish measuring from 307-386 mm long; egg diameters post fertilization ranged from 1.39 to 1.57 mm; hatching occurred in 27 hours at a water temperature of 23°C (Swedberg and Walburg 1970). Large-yolked, unfertilized eggs from a mature 5-year-old female averaged 0.72 mm in diameter (Daiber 1953).


Age/Size at maturation: Ages 4 to 6, with males measuring at least 203 mm TL and females 221 mm TL (Diaber 1953; Priegel 1969; Wrenn 1969). Dryer (2007) reported that maturation occurred most often during years 3 – 4, in Alabama populations.


Migration:  NA


Longevity: Rypel (2007) reported males up to 21 years and females up to 32 years in Alabama populations.


Food habits:  Primarily a benthic feeder, consuming insect larvae, crustaceans, fish, clams, and snails; molar-like pharyngeal teeth aid in masticating mollusks (Fremling 1980). Consumes mayflies and amphipods; fish and crayfish appear more frequently in diet of larger individuals (Daiber 1952). In Lake Winnebago, Wisconsin, midge larvae was main food item in diet of fish over 40 mm (1.6 inches), and copepods (Cyclops) were main food item for fish under 40 mm (1.6 inches; Preigel 1967a). In Lewis and Clark Lake (Missouri River), Daphnia and Cyclops were important food items for fish 6-15 mm long; bottom fauna became main food item in diet of fish > 20 mm (Swedberg and Walburg 1970). In a Tennessee reservoir without mollusks, diet switched to fish; all size groups collected included individuals that had consumed insects (larvae and pupae of chaoborines and small chironomids) or plankton (Leptodora; Dendy 1946). Will feed at all hours of the day (Priegel 1967b).


Growth: In an Alabama reservoir, estimated total lengths (mm) per age group were 81 (age 1), 145 (age 2), 198 (age 3), 241 (age 4), 295 (age 5), 348 (age 6), 406 (age 7), 475 (age 8), 551 (age 9), 607 (age 10), 648 (age 11), 676 (age 12), and 696 mm (age 13; Wrenn 1969). Average total lengths of fish from the Salt River, Missouri (lower station): 119 mm at the end of year 1, and 203, 257, and 279 mm at the end of years 2-4, respectively; averages from the Salt River (middle station): 130 mm at the end of year 1, and 218, 267, and 320 mm at the end of years 2-4, respectively (Purkett 1958).  In a study of sexual dimorphism in Alabama populations, females were significantly larger and had significantly higher growth rates than males. Males and females had similar growth rates from 0-4 years of age, but showed significantly different growth rates across subsequent ages; females grew significantly faster through adulthood (Rypel 2007).


Phylogeny and morphologically similar fishes:

Aplodinotus grunniens is the only North American freshwater representative of Family Sciaenidae (Barney 1926). 


Host Records:

Reported from Texas populations: Trematoda: Homalometron armatum; Nemata: Camallanus oxycephalus, Contracaecum, Rhabdochona decatrurensis, Spinitectus gracilis; Copepoda: Argulus flavescens, Ergasilus arthrosis (Mayberry et al. 2000)


Commercial or Environmental Importance

In Texas, this species is commonly referred to as the gaspergou, or simply “gou”. The otolith (inner ear bone) and pharyngeal teeth were regarded as good luck pieces by Native Americans; even today, otoliths are prized as jewelry pieces and charms, in some regions (Knapp 1953).


[Additional literature noting collection of this species from Texas locations includes, but is not limited to the following: Baughman (1946); Robinson (1959); Uyeno and Miller (1962); Swift (1968); Kasper and McClure (1976); Rose and Echelle (1981); Matthews et al. (1985); Kleinsasser and Linam (1987); Linam and Kleinsasser (1987); Linam et al. (1994); Li and Gelwick (2005).]



Barney, R.L. 1926. The distribution of the fresh-water sheepshead, Aplodinotus grunniens Rafinesque, in respect to the glacial history of North America. Ecology 7(3):351-364.

Baughman, J.L. 1946. An interesting association of fishes. Copeia 1946(4):263.

Cook, F.A. 1959.  Freshwater Fishes in Mississippi.  Mississippi Game and Fish Commission, Jackson. 239 pp.

Daiber, F.C. 1953. Notes on the spawning population of the freshwater drum (Aplodinotus grunniens Rafinesque) in western Lake Erie. American Midland Naturalist. 50:159-171.

Dendy J.S. 1946. Food of several species of fish, Norris Reservoir, Tennessee. Journal of Tennessee Academy of Science 21:105-127.

Edwards, R.J., and S. Contreras-Balderas. 1991. Historical changes in the ichthyofauna of the lower Rio Grande (Rio Bravo del Norte), Texas and Mexico. The Southwestern Naturalist 36(2):201-212.

Fremling, C.R.  1980.  Aplodinotus grunniens (Rafinesque), Freshwater drum.  pp. 756 in D. S. Lee, et al.  Atlas of North American Freshwater Fishes.  N. C. State Mus. Nat. Hist., Raliegh, i-r+854 pp.

Funk, J.L. 1955. Movement of stream fishes in Missouri. Trans. Amer. Fish. Soc. 85:39-57.

Gido, K.B., and W.J. Matthews. 2000. Dynamics of the Offshore fish assemblage in a southwestern reservoir (Lake Texoma, Oklahoma-Texas). Copeia 1000(4):917-930.

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.

Hay, O.P. 1883. On a collection of fishes from the lower Mississippi valley. Bull. U.S. Fish Comm. 2:57-75.

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

Holland, L.E. 1986. Distribution of early life history stages of fishes in selected pools of the Upper Mississippi River. Hydrobiologia 136(1):121-130.

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.

Kasper, T.C., and W.L. McClure. 1976. The Taylor Bayou local fauna (Pleistocene) near Houston. The Southwestern Naturalist 21(1):9-16.

Kleinsasser, L.J., and G.W. Linam. 1987. Fisheries use attainability study for Pine Island Bayou (Segment 0607). River Studies Report No. 6. Resource Protection Division. Texas Parks and Wildlife Department, Austin. 19 pp.

Knapp, F.T. 1953. Fishes found in the freshwater of Texas. Ragland Studio and Litho Printing Co., Brunswick, Georgia. 166 pp.

Li, R.Y. 2003. The influence of environmental factors on special and temporal variation of fish assemblages in the lower Brazos River, Texas. M.S. Thesis. Texas A&M University, College Station. 80 pp.

Li, R.Y., and F.P. Gelwick. 2005. The relationship of environmental factors to spatial and temporal variation of fish assemblages in a floodplain river in Texas, USA. Ecology of Freshwater Fish 14(4):319-330.

Linam, G.W., and L.J. Kleinsasser. 1987. Fisheries use attainability study for Cow Bayou (Segment 0511). River Studies Report No. 5. Resource Protection Division. Texas Parks and Wildlife Department, Austin. 12 pp.

Linam, G.W., J.C. Henson, and M.A. Webb. 1994. A fisheries inventory and assessment of Allens Creek and the Brazos River, Austin County, Texas. River Studies Report No. 12. Resource Protection Division. Texas Parks and Wildlife Department, Austin. 13 pp.

Matthews, W.J. 1984. Influence of turbid inflows on vertical distribution of larval shad and freshwater drum. Transactions of the American Fisheries Society 113:192-198.

Matthews, W.J., L.G. Hill, and S.M. Schellhass. 1985. Distribuiton of striped bass and other fish in Lake Texoma (Oklahoma-Texas) during summer stratification. Trans. Amer. Fish. Soc. 114:84-91.

Mayberry, L.F., A.G. Canaris, and J.R. Bristol. 2000. Bibliography of parasites and vertebrate host in Arizona, New Mexico, and Texas (1893-1984). University of Nebraska Harold W. Manter Laboratory of Parasitology Web Server. 100 pp.

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

Priegel, G.R. 1967a. Food of the freshwater drum, Aplodinotus grunniens, in Lake Winnebago, Wisconsin. Trans. Amer. Fish. Soc. 96(2):218-220.

Priegel, G.R. 1967b. The freshwater drum – its life history, ecology and management. Wis. Dep. Nat. Resour. Publ. 236. 15 pp.

Priegel, G.R. 1969. Age and rate of growth of the freshwater drum in Lake Winnebago, Wisconsin. Trans. Amer. Fish. Soc. 95(1):116-118.

Purkett, C.A., Jr. 1958. Growth of the fishes in the Salt River, Missouri. Trans. Amer. Fish. Soc. 87:116-131.

Rafinesque, C.S. 1819.  Prodrome de 70 nouveaux genres d’animaux decouverts dans l’interieur des Etats-Unis d’Amerique, durant l’annee 1818.  J. de Physique de Chimie et D’Histoire Naturelle 88:417-429.

Riggs, C.D., and E.W. Bonn. 1959. An annotated list of the fishes of Lake Texoma, Oklahoma and Texas. The Southwestern Naturalist 4(4):157-168.

Robinson, D.T. 1959. The ichthyofauna of the lower Rio Grande, Texas and Mexico. Copeia 1959(3):253-256.

Rose, D.R., and A.A. Echelle. 1981. Factor analysis of associations of fishes in Little River, Central Texas, with an interdrainage comparison. American Midland Naturalist 106(2):379-391.

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

Rypel, A.L. 2007. Sexual dimorphism in growth of freshwater drum. Southeastern Naturalist 6(2):333-342.

Scott, W.B., and E.J. Crossman. 1973. Freshwater Fishes of Canada. Fisheries Research Board of Canada, Ottawa. Bulletin 184:966 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.

Swedberg, D.V., and C.H. Walburg. 1970. Spawning and early life history of the freshwater drum in Lewis and Clark Lake, Missouri River. Trans. Amer. Fish. Soc.99(3):560-570.

Swift, C. 1968. Pleistocene freshwater fish from Ingleside Pit, San Patricio County, Texas. Copeia 1968(1):63-69.

Uyeno, T., and R.R. Miller. 1962. Pleistocene fishes from a Trinity River terrace, Texas. Copeia 1962(2):338-345.

Wailes, B.L.C.  1854.  Report on the agriculture and geology of Mississippi.  E. Barksdale, State Printer, Jackson

Willis, D.W. and L.D. Jones. 1986. Fish standing crops in wooded and nonwooded coves of Kansas reservoirs. N. Amer. J. Fish. Managm. 6(1):105-108.

Wrenn, W.B. 1969. Life history aspects of smallmouth buffalo and freshwater drum in Wheeler Reservoir, Alabama. Proc. S.E. Assoc. Game Fish Comm. 22:479-495.

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.