Picture by Chad Thomas, Texas State University-San Marcos

Hybognathus nuchalis

Mississippi silvery minnow

Type Locality

Quincy, IL (Agassiz 1855).

Etymology/Derivation of Scientific Name

Hybognathus, Greek, “swollen jaw;” nuchalis, Latin, pertaining to the nape (Pflieger 1997).

Synonymy

H. argyritis removed from synonomy of H. nuchalis by Pflieger (1971). The Committee on Names of Fishes (Robins et al. 1980) recommended the addition of Mississippi to the common name, a modifier indicative of its geographic range (Becker 1983).

Hybognathus nuchalis Agassiz 1855:224.

Triodon amnigenus Hay 1883:68.

Characters

Maximum size: To 180 mm (7.09 in) (Page and Burr 1991).

Coloration:  Belly and sides silvery. Iridescent, green-gold mid-dorsal stripe is broad and present anterior, as well as posterior to the dorsal fin (Fingerman and Suttkus 1961). Breeding male with light yellow along the sides and lower fins, and small tubercles on the body and fins (Becker 1983).

Counts: Pharyngeal teeth 0,4-4,0 (Page and Burr 1991). 34-41 lateral line scales; fewer than 10 dorsal fin soft rays (Hubbs et al. 1991); usually 8 anal soft fin rays; 15-16 pectoral fin soft rays (Fingerman and Suttkus 1961). 11-15 scale rows across belly (counted just in advance of pelvic insertion, excluding lateral line scales; Hubbs et al.1991).

Body shape: Subterete, with rounded profile (Fingermann and Suttkus 1961).

Mouth position: Small, slightly subterminal mouth, rear edge of mouth in front of eye (Page and Burr 1991).

Morphology: Scales with 10 radii (grooves); head width about equal to distance from tip of snout to back of eye;  eye contained in snout about one and one-half times; first obvious dorsal fin ray a thin splint, closely attached to the following well developed but unbranched ray; lower lip thin; lateral line usually not decurved, either straight or with broad arch; premaxillaries protractile; upper lip separated from skin of snout by a deep groove continuous across the midline; distance from origin of anal fin to end of caudal peduncle contained two and one-half or fewer times in distance from tip of snout to origin of anal fin (Hubbs et al.1991). In spring, the nuchal region is somewhat swollen (Forbes and Richardson 1920). Intestine long and coiled, more than twice the length of the body (Hubbs et al.1991).

Distribution (Native and Introduced)

U.S. distribution: Mississippi basin from MN south to Brazos River, TX, and Mobile Bay drainage, AL (H. nuchalis); Rio Grande drainage of NM and TX (H. amarus; Pflieger 1980).

Texas distribution: Found in eastern TX streams, from the Brazos River eastward and northward to the Red River (Hubbs et al 1991).

Abundance/Conservation status (Federal, State, Non-governmental organizations)

Populations in southern drainages are currently stable (Warren et al. 2000).

Habitat Associations

Macrohabitat: Common in pools and backwaters of medium to large streams with low or moderate gradients (Pflieger

1980). In Texas, adults likely to inhabit smaller tributary streams and not the Brazos River main stem (Winemiller et al.

2004). Etnier and Starnes (1993) note that main stem rivers may be important to the early development or another aspect of life history.

Mesohabitat: Moderate current; silty, muddy, or rocky substrate (Fingerman and Suttkus 1961).

Biology

Spawning season: January through April (Burr and Mayden 1982). In Wisconsin, from the end of April or early May until at least the end of July. Females with mature eggs 0.8 mm (0.03 in) diameter were taken from two creeks, tributaries to the lower Wisconsin River, in mid and late July; no gravid females were found in collections made in August and September (Becker 1983).

Spawning habitat: Calm waters along the edge of streams and in the backwaters and overflow pools of large rivers (Burr and Mayden 1982). Adams and Hankinson (1926) note breeding principally in creeks and rivers in shallow water, in or near riffles.

Spawning Behavior: Lithopelagophils; rock and gravel spawners with pelagic free embryos. (Simon 1999).

Fecundity: In the Wisconsin River, in June, an individual , 102 mm (4.02 in) TL and 8.84 g, had ovaries 9.3% of the body weight, which contained 2, 054 yellow mature eggs 0.8-0.9 mm (0.03-0.04 in) diameter. A second female, 107 mm (4.21 in) TL and 10.75 g, held 3,105 mature eggs 0.7-0.9 mm (0.03-0.04 in) diameter; the ovaries were 9.3% of the body weight. No smaller, white, immature eggs were observed (Becker 1983).

Age at maturation: Two years (Becker 1983). Some females reach maturity at age 1 (Mansueti and Hardy 1967).

Migration: No information at this time.

Growth and Population Structure: In Wisconsin, reported growth averaged 75 mm (2.95 in) TL at age 1 and 100 mm (3.94 in) TL at age 2 (Becker 1983).

Longevity: 2 years (Becker 1983).

Food habits: Feeds in large schools near bottom, ingesting mud and bottom ooze from which it digests algae and other organic matter (Forbes and Richardson 1920). The long intestine facilitates the digestion of algae and other plant material (Page and Burr 1991). Hlohowskyj et al. (1989) indicated that the pharyngeal papillae of members of Hybognathus are arranged in an elaborate pattern and may be used as a filtering apparatus for trapping small food items.

Phylogeny and morphologically similar fishes:

      Hybognathus nuchalis  body shape is subterete; that of H. hayi is compressed. H. hayi has an angular profile; H. nuchalis

      is rounded and individuals of the species lack diamond-appearing scales. Melanophores of the anterior part of the lateral

      band of H. hayi are small and only slightly larger than the melanophores on the upper part of the sides and back, while the

      large melanophores of the anterior part of the lateral band of H. nuchalis are usually noticeably larger than the melanophores

      above the band. The median dorsal stripe in front of the dorsal fin is wider and darker in H. nuchalis. H. hayi has a much

      shorter intestine in proportion to the standard length than does H. nuchalis. Snout is broadly rounded in H. hayi and can

       hardly be seen when specimens are viewed ventrally, while the snout of H. nuchalis is more pointed and projects anteriorly

       beyond the upper lip by about twice the thickness of the upper lip (Fingerman and Suttkus 1961).

Host Records

Trematoda (Posthodiplostomum minimum (Texas) (Mayberry et al., 2000).

Commercial or Environmental Importance

Commercially used as bait fish for larger game fish of inland fisheries (Becker 1983).

References

Adams, C. C., and T. L. Hankinson. 1926. Annotated list of Onieda Lake fish. pp. 283-542 In: Bull. N. Y. State Coll. For., Roosevelt Wildl. Ann. 1(1-2).

Agassiz, L. 1855. Synopsis of the ichthyological fauna of the Pacific slope of North America, chiefly from the collections made by the U.S. Expl. Exped. under the command of Capt. C. Wilkes, with recent additions and comparisons with eastern types. Amer. J. Sci. Arts, ser. 2, 19:71-99, 215-231

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

Burr, B. M. and Mayden. 1982. Fishes of Alabama and the Mobile Basin. Geological Survey of Alabama. Tuscaloosa, Alabama.

Fingerman, S. W., and R. D. Suttkus. 1961. Comparison of Hybognath hayi Jordan and Hybognatus nuchalis Agsiiz. Copeia. 1961(4):462-467

Forbes, S. A. and R. E. Richardson. 1920. The fishes of Illinois. State of Illinois Natural History Survey Division, Urbana.

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

Hlohowskyj, C. P., M. M. Coburn, and T. M. Cavender. 1989. Comparison of a pharyngeal filtering apparatus in seven species of the herbivorous cyprinid genus, Hybognathus (Pisces: Cyprinidae). Copeia 1989:172-183.

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

Mansueti, A. J., and J. D. Hardy. 1967. Development of fishes of the Chesapeake Bay region. Univ. Maryland, Baltimore, Natural Resour. Inst., Part. I. 202 pp.

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 pp. 1-100.

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

Pflieger, W. L. 1971. A distributional study of Missouri fishes. Mus. Nat. Hist. Univ. Kans. 20(3):225-570.

Pflieger, W. L. 1980. Hybognathus nuchalis (Agassiz), Central silvery minnow. pp. 177 in D. S. Lee, et al. Atlas of North American Freshwater Fishes. N. C. State Mus. Nat. Hist., Raleigh, i-r+854 pp.

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

Robins, C. R., R. M. Bailey, C. E. Bond, J. R. Brooker, E. A. Lachner, R. N. Lea, and W. B. Scott (Common names of fishes). 1980. A list of common and scientific names of fishes from the United States and Canada. 4^th ed. American Fisheries Society, Bethesda, MD. Special Publ. No. 12. 174 pp.

Simon, T. P. 1999. Assessing the sustainability and biological integrity of water resources using fish communities. CRC Press. Boca Raton; London; New York; Washington.

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.

Winemiller, K. O., F. P. Gelwick, T. Bonner, S. Zueg, and C.Williams. 2004. Response of Oxbow Lake Biota to Hydrologic Exchanges with the Brazos River Channel. Texas Agricultural Experiment Station and Texas State University to Texas Water Development Board.