The river redhorse, Moxostoma carinatum, is a large fish that occurs in swift waters of medium to large rivers, and enters smaller streams only during the breeding season. The destruction of a large number of big rivers in Tennessee by impoundment has resulted in a considerable decrease in numbers of this fish.

This member of the sucker family is a silvery fish with bright red caudal and dorsal fins and orange to red lower fins. The dorsal fin has a slightly concave margin. Nuptial males develop large tubercles on the anterior and lateral areas of the snout and cheek, and occasionally on the opercles. Smaller tubercles may be present on the gular area and on top of the head. Anal and caudal fin rays develop moderate sized tubercles on all rays.

Size: maximum total length 736 mm (29 in.) and 4.8 kg (10.5 lb)(Trautman 1957); Tatum and Hackney (1970) report weights up to 7.3 kg (16 lbs) from Duck River, Tennessee, and Flint River, Alabama Color: silvery with bright red caudal and dorsal fins and orange to red lower fins Fins: dorsal fin rays 13 (12-15); pectoral fin rays 16-17 (15-18); total pelvic fin rays 18 (16-20); anal fin rays 7 Lateral-line scales: 42-44 (41-47) Gill rakers: 19-31 (26-31 in specimens larger than 150 mm standard length) Vertebrae: 41-44 Pharyngeal arch: heavy with teeth enlarged and molariform Lips: plicate (ridged), lobes of lower lip meet to form an angle of about 120 degrees

The river redhorse has been reported to spawn in mid-April at temperatures of 71-76 degrees F. (22-24 degrees C.) in the Cahaba River, Alabama. Males were observed constructing nests, or redds, in gravel shoal areas with water depths of 0.15-1.07 m. The redds were constructed by sweeping with the caudal fin, pushing gravel with the head, and using the mouth, presumably to move pebbles. Redds were tended by individual males and numbered 8 or more per spawning shoal; neighboring redds often overlapped. When a female entered the redd, the attendant male began darting back and forth, and was soon joined by another male, who also began darting about. The female then took a position between the two males and the three engaged in coordinated vibrations that resulted in eggs being released, fertilized, and buried in gravel. Fecundity of females ranging in size from 455-563 mm (18-22 in.) ranged from 6,000-23,000 eggs (Hackney et al. 1968). Redd construction was not observed in river redhorse spawning behavior in the Tennessee River drainage (pers. comm. R. E. Jenkins). Sexual maturity occurred at age 3 at about 415 mm total length (16 in.) in a Cahaba River population that averaged 488 mm (19 in.) in summer of the 4th year (Tatum and Hackney 1970). Based on length frequencies of small wild specimens (Jenkins 1970), and a reanalysis of scale annuli used to age the Cahaba River redhorses, Jenkins and Burkhead (1994) suggest that river redhorses may grow slower, mature later, and live much longer than originally reported by Tatum and Hackney (1970). Life span of the river redhorse is 8-12 years (Tatum and Hackney 1970; Carlander 1969). Adult river redhorses feed predominantly on small bivalve molluscs which they crush with their heavy pharyngeal teeth. Hackney et al. (1968) reported the Cahaba River population to feed largely on the introduced Asiatic clam, Corbicula, in addition to occasional benthic insect larvae.

The river redhorse is rare, and has been reported to have been collected only 5 times in the Little Tennessee River and Abrams Creek systems (Simbeck 1990). Three of these collections were field identifications; because of problems with field identifications of Park Moxostoma, all records not represented by preserved specimens are suspect.

References:

Carlander, K. D. 1969. Handbook of freshwater fishery biology. Vol. 1. Life history data on freshwater fishes of the United States and Canada, exclusive of the Perciformes. Iowa St. Univ. Press, Ames.

Etnier, David A. and Wayne C. Starnes. 1993. The Fishes of Tennessee. University of Tennessee Press. Knoxville, Tennessee.

Hackney, P. A., W. M. Tatum, and S. L. Spencer. 1968. Life history study of the river redhorse, Moxostoma carinatum (Cope), in the Cahaba River, Alabama, with notes on the management of the species as a sport fish. Proc. 21st Ann. Conf. SE Assoc. Gam

Jenkins, R. E. 1970. Systematic studies of the catostomid fish tribe Moxostomatini. Doctoral dissertation. Cornell University, Ithaca.

Jenkins, Robert E. and Noel M. Burkhead. 1994. Freshwater Fishes of Virginia. American Fisheries Society. Bethesda, Maryland

Jenkins, R. E. Ichthyologist, Roanoke College, Salem, Virginia. Personal Communication.

Simbeck, Damien J. 1990. Distribution of the Fishes of the Great Smoky Mountains National Park. Master of Science Thesis, University of Tennessee.

Tatum, W. M. and P. A. Hackney. 1970. Age and growth of river redhorse, Moxostoma carinatum (Cope), from the Cahaba River, Alabama. Proc. 23rd Ann. Conf. SE Assoc. Game & Fish Comm.:255-261.

Trautman, M. B. 1957. The fishes of Ohio. Ohio St. Univ. Press, Columbus.