Picture by Chad Thomas, Texas State University-San Marcos

Hybognathus amarus

Rio Grande silvery minnow

Type Locality

See Girard (1856).

Etymology/Derivation of Scientific Name

No information at this time.

Synonymy

No information at this time.

Characters

Maximum size: 89 mm (3.50 in) TL

Coloration: Dorsal region brown to olive with a broad and dark mid-dorsal stripe; lateral region silvery with dark pigmentation forming a diffuse mid-lateral stripe; ventral region white.

Counts: Pharyngeal teeth in main row typically 4-4; scales with 8 radii; 11-15 scale rows across belly (counted just in advance of pelvic insertion, excluding the lateral line scales); fewer than 45 lateral line scales; fewer than 10 soft rays on dorsal fin (Hubbs et al. 2008).

Body shape: Head width about equal to distance from tip of snout to back of eye; eye contained in snout about 1.5 times; eye shorter than snout; distance from anal fin origin to end of caudal peduncle goes 2.5 or fewer times in distance from tip of snout to anal fin origin (Hubbs et al. 2008).

External morphology: Predorsal scale rows not crowded except for fish with 9 or more anal fin rays; first obvious dorsal fin ray a thin splint, closely attached to the following well developed but unbranched ray, especially at tip; lower lip thin, without a fleshy lobe; lateral line usually not decurved, either straight or with a broad arch; premaxillaries protractile; upper lip separated from skin of snout by a deep groove continuous across the midline; cartilaginous ridge of lower jaw hardly evident and not separated by a definite groove from the lower lip (Hubbs et al. 2008).  Intestine long and coiled, more than twice standard length (Hubbs et al. 2008).

Distribution (Native and Introduced)

U.S. distribution: Once abundant throughout the Rio Grande and Pecos basins; it now exists only in scattered Rio Grande locations in New Mexico (Hubbs et al. 2008).

Texas distribution: Apparently extirpated in Texas (Rio Grande and Pecos basins; Hubbs et al. 2008).

Abundance/Conservation status (Federal, State, NGO)

State Endangered (Texas); Federally Endangered (Hubbs et al. 2000); presumably extirpated in Texas. Listed as Endangered by the American Fisheries Society; status has declined since 1989; categories of threats: present or threatened destruction, modification, or reduction of habitat or range; disease or parasitism; other natural or anthropogenic factors that affect the existence of this species, including impacts of nonidigenous organisms, hybridization, competition, and/or predation (Jelks et al. 2008).

Habitat Associations

Macrohabitat: No information at this time.

Mesohabitat: No information at this time.

Biology

Spawning season: No information at this time.

Spawning habitat: No information at this time.

Spawning Behavior: No information at this time.

Fecundity:  No information at this time.

Age at maturation:  No information at this time.

Migration: No information at this time.

Growth and Population structure:  No information at this time.

Longevity: No information at this time.

Food habits: No information at this time.

Phylogeny and morphologically similar fishes

 No information at this time.

Host Records

No information at this time.

Commercial or Environmental Importance

No information at this time.

References

Bestgen, K. R., D. L. Propst. 1996. Redescription, geographic variation, and taxonomic status of the Rio Grande silvery minnow, Hybognathus amarus (Girard 1856). Copeia 1996(1):41-55.

Girard, C.F. 1856. Researches upon the Cyprinoid fishes inhabiting the fresh waters of the United States of America, west of the Mississippi Valley, from specimens in the Museum of the Smithsonian Institution. Proceedings of the Academy of Natural Sciences of Philadelphia (1856) 8(5):165-213.

Hubbs, C., R.J. Edwards, and G.P. Garrett. 2008. An annotated checklist of the freshwater fishes of Texas, with keys to identification of species. Texas Journal of Science, Supplement, 2^nd edition 43(4):1-87.

Jelks, H.L., S.J. Walsh, N.M. Burkhead, S. Contreras-Balderas, E. Diaz-PArdo, D.A. Hendrickson, J. Lyons, N.E. Mandrak, F. McCormick, J.S. Nelson, S.P. Platania, B.A. Porter, C.B. Renaud, J.J. Schmitter-Soto, E.B. Taylor, and M.L. Warren, Jr. 2008. Conservation status of imperiled North American freshwater and Diadromous Fishes. Fisheries 33(8):372-407.