Moxostoma congestum

gray redhorse



Type Locality

Rio Salado, Texas (Baird and Girard 1854)


Etymology/Derivation of Scientific Name

Moxostoma, Greek for "sucking mouth"; congestum, Latin for "swollen" probably a reference to the "full" lower lip (Tomelleri and Eberle 1990).



Castostomus congestum (Baird and Girard 1854).

Ptychostomus congestus (Girard 1857).

Moxostomua congestum (Jordan 1885).

Scartomyzon conjestus (Miller et al. 2005).



Maximum size: 514 mm (Jenkins 1980).


Coloration: Distal one-half of dorsal fin membranes dusky; caudal fin dusky; lower sides olive to yellow; caudal fin without black streak (Hubbs et al. 1991). Black grayish or yellowish brown to greenish; sides silvery; abdomen whitish. Lower fins occasionally tinged with red; membranes of dorsal fins streaked with black (Sublette et al.1990).


Counts: 44-46 scales along the lateral line; dorsal fin rays 11 or 12 (Hubbs et al. 1991); pectoral rays15-16; pelvic rays 9; anal rays 6-7; caudal rays 18; approximately 55 teeth per arch (pharyngeal teeth in a single row; medial teeth cylindrical, weakly bifurcalte; teeth 1-3 straplike; masticatory pad; Sublette et al.1990).


Body shape: Terete (Sublette et al. 1990). Pectoral fin length equal to head length; width of eye contained four to four and one-half times in head length; dorsal fin base less than one-fourth standard length; air bladder with 3 chambers (Hubbs et al. 1991).


Mouth position: Inferior, small, extending posteriorly to a point just anterior to the nares. Lips plicate, papillae replacing the plicae in corners of the mouth; halves of lower lips meet at an acute angle to form a deep median groove (Sublette et al. 1990).


External morphology: Lateral line complete and well developed in adults (Hubbs et al. 1991). In males, nuptial tubercles are present on the anal fin and on the ventral lobe of the caudal fin as well as a few weak tubercles on the pectorals (Sublette et al. 1990).


Distribution (Native and Introduced)

U.S. distribution: Range includes Gulf of Mexico coastal streams as far south as the Rio Soto la Marina in Mexico and the Rio Grande tributaries in New Mexico, although it appears to be declining in Mexico (Sublette et al. 1990; Edwards 1997; Hubbs et al. 1991).


Texas distribution: Restricted in the state to the streams within the Edwards Plateau including the Brazos, Colorado, Guadalupe, San Antonio, Nueces and Rio Grande drainages (Jenkins 1980; Hubbs et al. 1991).


Abundance/Conservation status (Federal, State, NGO)

Populations in southern United States are considered currently stable (Warren et al. 2000). Special Concern status in Texas (U.S.A.) and in Coahila, Nuevo Leon, and Tamaulipas (Mexico); status due to present or threatened destruction, modification, or curtailment of species’ habitat or range (Williams et al. 1989). Classified as State Endangered, Group II, in New Mexico (21 May 1976; Sublette et al. 1990); large numbers of this species were eliminated in the Pecos River through past “rough fish” eradication programs in New Mexico, and a more current threat is the depletion of surface water.


Habitat Associations

Macrohabitat: Generally found in upland and lowland rivers and streams (Conner and Sutkus 1986).


Mesohabitat: Found in rock, sand, or gravel bottomed pools and deep runs of creeks and rivers; occurs also in some reservoirs. Young and subadults form loose schools in riffles and gravelly runs. Adults usually found in stream pools with firm substrate of sand or silt, sometimes with moderate turbidity (Hubbs et al. 1953; Edwards 1997). These stream pools often rather deep with slow-moving currents and little vegetation. Adults and subadults may often be observed moving both upstream and downstream between large pools, frequently spending considerable time slowly foraging while moving across runs and other shallow water environments before settling into new pool habitats (Cowley and Sublette 1987; Edwards 1997). In the Blanco River, species was most abundant in pools of tributaries and in the impoundment above a low-head dam (Bean 2006). M. congestum seeks quieter, deeper habitats, but seems also to prefer flowing clear-water streams (Rose and Echelle 1981). Species was negatively correlated with the piscivorous Micropterus dolomieu (smallmouth bass) in the Devils River, Texas (Robertson and Winemiller 2003). Hubbs and Wauer (1973) noted the occasional seasonal abundance of M. congestum (fish less than 20 mm SL present in collections during this study) in the clear and thermally stable Tornillo Creek, Texas, is clearly at seasons when Fundulus are scarce.



Spawning season: Results from a study of fish collected in a Texas Hill Country stream and a central Texas reservoir indicated that M. congestum spawns over two distinct periods first in late February or early March and again in late April or early May (Bean 2006; Bean and Bonner 2008).Young-of-year M. congestum (less than 20 mm SL) were collected from Tornillo Creek, Texas in June suggesting late May reproduction (elsewhere in Texas young M. congestum abound at that time and ripe adults are collected in February and March; Hubbs and Wauer 1973). Nuptial tuberculation indicates spring spawning (Jenkins 1980); Martin (1986) reported spawning to occur from March to April, in Texas, with water temperatures of 16.5-21.5º C recorded for this period.


Spawning habitat: Clear creeks were the adults have migrated; in the tail of pools, just above riffles over clean cobble-gravel-pebble bottoms, in water approximately 3-.6 m deep (Martin 1986; Miller et al. 2005).


Spawning behavior: Spawns a single clutch of eggs or multiple clutches of the same egg cohort over a brief spawning period (Bean 2006; Bean and Bonner 2008). In spawning runs in Walnut Creek, Texas, two to seven fish closely aggregate with their heads turned upstream. Their bodies are pressed together posteriorly in amplexus and with bodies quivering, the group moves forward over the substratum. Many such runs of about half a meter are made, each lasting about five seconds (Martin 1986).




Age at maturation: Mature Moxostoma congestum females collected from a Texas Hill Country stream and a central Texas reservoir ranged from 260-497 mm TL and males ranged from 285-468 mm TL. Developing oocytes were not found in individuals <392 mm, suggesting M. congestum is a late maturing species (Bean 2006; Bean and Bonner 2008).


Migration: Hubbs and Wauer (1973) suggested young M. congestum migrate from the Rio Grande River to the creek nursery area of Tornillo Creek, Texas, as no adults would be expected in such a small stream. Edwards (1997) stated that this species moves upstream and into smaller creeks to spawn in the spring (Martin 1986; Tomelleri and Eberle 1990).


Growth and Population structure: In fish collected from a Texas Hill Country stream and a central Texas reservoir there was no difference in mean TL between males and females; sex ratio 1:1 (Bean 2006; Bean and Bonner 2008).


Longevity: Edwards (1997) has observed a 5-year-old individual and suggests species may live beyond that age.


Food habits: Moxostoma congestum collected from a Texas Hill Country stream and a Texas reservoir was opportunistic benthic invertivore with diet differing between stream and reservoir habitats and among seasons.  Diet consisting of aquatic insects (47%, unweighted mean across months; Diptera and Ephemeroptera larvae, Tricoptera, Odonata, Coleoptera, Megaloptera), mollusks (42%; Corbicula fluminea, other gastropods and bivalves), amphipods (5%), ostracods (3%), fish (1%), Hydrachnida (<0.1%), algae (<0.1%), plant seeds (0.1%), and unidentifiable insect parts (2%). Across months, aquatic insects comprised the majority of diet from October to May; from June to September the main food item was mollusks; amphipods were relatively abundant in stomachs in October (17%) and December (28%); ostrocods were abundant in December (14%) and March (19%; Bean 2006; Bean and Bonner 2008). Among aquatic insects dipterans, particularly chironomids, were most common food item suggesting feeding takes place in calm waters of pools or stream edges (Timmons and Ramsey 1983; Bean 2006; Bean and Bonner 2008). Diet includes algae, crayfish snails, small clams, larval insects and other food organisms associated with firm substrates. Feeding seems non-selective; individuals consume foods in the abundances in which they occur in their environment. M. congestum feeds at times over riffles, as caddisflies found in stomachs of this species are generally restricted to riffle habitat (Cowley and Sublette 1987; Tomelleri and Eberle 1990; Edwards 1997).


Phylogeny and morphologically similar fishes

Moxostoma congestum most closely related to Moxostoma austrinum, the West Mexican redhorse (Robins and Raney 1957), but M. austrinum has usually 36-41 scales around body (at dorsal fin origin; versus 36-41), and dark cresents on upper body scales (Page and Burr 1991). The black-banded membranes in the dorsal and caudal fins of the gray redhorse distinguish it from all other species of redhorses inhabiting the central U.S. (Tomelleri and Eberle 1990). The grey redhorse can be separated from other terete suckers by the plicate folds on the lips and membranes of the dorsal fins streaked with black (Sublette et al. 1990).


Host Records

In Texas: Cestoda - Lissorchis hypentelii; Trematoda - Posthodiplostomum minimum; Nemata -Spyroxys contorta; Acanthocephala - Pomphorhynohus bulbocolli (Mayberry et al 2000).


Commercial or Environmental Importance

Habitat degradation is a concern for M. congestum (Williams et al. 1989), yet species persists in habitats disturbed by low-head dam and mainstem reservoir construction as a result of its opportunistic feeding strategy which allows adaptability to lentic systems (Bean et al. 2007; Bean and Bonner 2008). If species was locally extirpated due to reduced discharge or reduced water quality caused by excessive groundwater pumping and drought, the presence of low-head dams may inhibit recolonization (Bean 2006; Bean and Bonner 2008).


[Additional literature noting collection of this species from Texas locations includes, but is not limited to the following: Hubbs (1954; 1957); Devils River (Harrell 1978); Pinto Creek (Edwards 1991); Hidalgo County (Edwards and Contreras-Balderas 1991); Devils River (Cantu and Winemiller 1997).]



Baird, S.F., and C. Girard. 1854. Descriptions of new species of fishes collected in Texas, New Mexico, and Sonora, by Mr. John H. Clark, on the United States and Mexico boundary survey, and in Texas by Capt. Van Vliet, U.S.A., second part. Proc. Acad. Nat. Sci. Phila. 7:24-29.

Bean, P.T. 2006. Spatial and temporal patterns in the fish assemblage of the Blanco River, Texas, and Reproductive ecology and diet of the grey redhorse, Moxostoma congestum. M.S. Thesis. Texas State University – San Marcos. San Marcos, Texas, 58 pp.

Bean, P.T., and T.H. Bonner. 2008. Diet and reproduction of the gray redhorse (Moxostoma congestum) in a Texas Hill Country stream and reservoir. Journal of Freshwater Ecology 23(3):397-404.

Bean, P.T., T.H. Bonner, and B.M. Littrell. 2007. Spatial and temporal patterns in the fish assemblage of the Blanco River, Texas. Texas Journal of Science 59:179-200.

Cantu, N.E.V., and K.O. Winemiller. 1997. Structure and habitat associations of Devils River fish assemblages. Southwestern Naturalist 42(3):265-278.

Conner, J.V., and R.D. Suttkus. 1986. Zoogeography of freshwater fishes of the western gulf slope of America. pp. 413-456 in: C.H. Hocutt and E.O. Wiley, ed. The zoogeography of North American freshwater fishes. John Wiley and Sons, Inc., New York, N.Y.

Cowley, D.E. and J.E. Sublette. 1987. Food habits of Moxostoma congestum (Baird and Girard) and Cycleptus elongatus (Lessueur) (Catostomidae: Cyprinformes) taken from Black River Eddy County, New Mexico. Southwest. Nat.32: 411-13.

Edwards, R.J. 1991. Ecological profiles for selected stream-dwelling Texas freshwater fishes IV. Report to the Texas Water Development Board. 19 pp.

Edwards, R. J. 1997. Ecological profiles for selected stream-dwelling Texas freshwater fishes. Report to the Texas Water Development Board. 89 pp.

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.

Girard, C. (1856) 1857. Researches upon the cyprinid fishes inhabiting the fresh waters of the United States of America west of the Mississippi Valley, from specimens in the Smithson. Institution. Proc. Acad. Nat. Sci. Phila. 18:165-213.

Harrell, L.H. 1978. Response of the Devil’s River (Texas) fish community to flooding. Copeia 1978(1):60-68.

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Hubbs, C., and R. Wauer. 1973. Seasonal changes in the fish fauna of Tornillo Creek, Brewster County, Texas. The Southwestern Naturalist 17(4):375-379.

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Jordan, D.S. 1885. Identification of the species of Cyprinidae and Catostomidae, described by Dr. Charles Girard, in the Proceedings of the Academy of Natural Sciences of Philadelphia for 1856. Proc. U.S. Natl. Mus. 8:118-127.

Martin, R.F. 1986. Spawning behavior of the gray redhorse, Moxostoma congestum (Pisces: Catostomidae) in Central Texas. Southwest. Nat. 31: 399-401.

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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.

Robertson, M.S., and K.O. Winemiller. 2003. Habitat associations of fishes in the Devils River, Texas. Journal of Freshwater Ecology 18(1):115-127.

Robins, C. R. and E. C. Raney. 1957. The systematic status of the suckers, of the genus Moxostoma from Texas, New Mexico, and Mexico. Tulane Studies in Zoology 5: 291-318.

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.

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Timmons, T.J., and J.S. Ramsey. 1983. Life history and habitat of the blackfin sucker, Moxostoma atripinne (Osteichthyes: Catostomidae). Copeia 1983:538-541.

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