Information Last Reviewed Spring 2007
Phylum: Chordata
Class: Actinopterygii
Order: Cypriniformes
Family: Cyprinidae
Genus: Macrhybopsis
Species found in the United States: M. aestivalis, M. australis, M. gelida (USFWS candidate species), M. hyostoma, M. marconis, M. meeki (USFWS candidate species), M. storeriana, and M. tetranema
Morphology
Slender, compressed body usually silvery with or without dark markings 
Mouth directed downward
Barbels present at corner of mouth are relatively inconspicuous to the naked eye except in M. aestivalis
8 anal fin rays
8 dorsal fin rays
Lower portion of tail fin with faint to dark black pigment
Maximum body size across species ranges from 7.6-23 cm
Distinguishing Characteristics
Genus Macrhybopis can be distinguished from the following invasive carps by:
Bighead and silver carp have eyes located forward on the head and unusually low, dorsal and anal fins preceded by a spine-like ray, 13 anal fin rays, a midventral keel on the abdomen, mouth directed forward, and individuals commonly reaching a maximum size greater than 23 cm. 
Grass carp has a thick, cylindrical body, larger scales, 8-9 anal fin rays, mouth directed forward, and individuals commonly reaching a maximum size greater than 23 cm
Common carp has two long, conspicuous barbels on the upper jaw, serrated spines at the anterior of the dorsal and anal fins, 15-23 dorsal fin rays, and yellow-orange coloration in the caudal, anal, and pelvic fins
Black carp has a thick, cylindrical body, an anal fin comprised of 8-10 rays, relatively large scales, mouth directed forward, and a maximum body size greater than 23 cm. 
Bottom-oriented fishes occupying swift currents over sand and gravel substrates in medium to large, turbid rivers; M. storeriana also occurs in riverine backwaters and lakes.
Primarily found within the central and eastern United States in the Mississippi River basin and Gulf Slope drainages from Florida to Texas and New Mexico. 
M. aestivalis is relatively common in the Rio Grande basin and Rio San Fernando drainage in New Mexico and Texas.
M. gelida and M. meeki are primarily found in the Missouri River and the middle Mississippi River, occurring sporadically in the lower Mississippi River; they are rare throughout their ranges but may be locally common in the Missouri River.
M. storeriana is widespread and common in the Lake Erie drainage, Red River of the North, and throughout much of the Mississippi River basin and some Gulf Slope drainages.
M. tetranema is rare in the middle and upper portion of the Arkansas River basin. 
M. hyostoma is widespread in the Mississippi River basin and western Gulf Slope drainages; it is rare in the Arkansas River basin.
M. australis is uncommon in the upper Red River basin of Oklahoma. 
M. marconis occurs in the San Antonio, Guadalupe, and Colorado river drainages of Texas.
Eisenhour, D.J. 1999. Systematics of Macrhybopsis tetranema (Cypriniformes: Cyprinidae). Copeia 1999:969-980.
Eisenhour, D. J. 1997. Systematics, variation, and speciation of the Macrhybopsis aestivalis complex (Cypriniformes: Cyprinidae) west of the Mississippi River. Ph.D. dissertation, Southern Illinois University, Carbondale.
Etnier, D.A., and W.C. Starnes. 1993. The Fishes of Tennessee. The University of Tennessee Press, Knoxville. 681 pp.
Lee, D.S., C.R. Gilbert, C.H. Hocutt, R.E. Jenkins, D.E. McAllister, and J.R. Stauffer, Jr. 1980. Atlas of North American Freshwater Fishes. North Carolina Biological Survey, North Carolina. 866 pp.
Miller, R.J., and H.W. Robison. 2004. Fishes of Oklahoma. The University of Oklahoma Press, Norman. 450 pp.
Nico, L. G., J.D. Williams, and H.L. Jelks. 2005. Black carp: biological synopsis and risk assessment of an introduced fish. American Fisheries Society, Special Publication 32, Bethesda, Maryland. 337 pp.
Page, L.M. and B.M. Burr. 1991. A field guide to freshwater fishes of North America. Houghton Mifflin Company, Boston. 432 pp.
Pflieger, W.L. 1997. The Fishes of Missouri. Missouri Department of Conservation, Jefferson City. 372 pp.