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Montana Field Guides

Flathead Chub - Platygobio gracilis

Native Species

Global Rank: G5
State Rank: S5
(see State Rank Reason below)

Agency Status


External Links

State Rank Reason (see State Rank above)
Currently ranked a S5 because it is common, widespread, and abundant (although it may be rare in parts of its range). Not vulnerable in most of its range.
General Description
The flathead chub has one of the greatest north-south distributions of any of the minnows. It extends from New Mexico to the northern Yukon Territory in Canada. Here in Montana it is found in the plains and foothill streams of our Missouri-Yellowstone River complex and is an indicator species of the Medium Warmwater River Fish Assemblage. Its most conspicuous features are a barbel or "whisker" at each corner of its mouth, flattened head and streamlined appearance. The sleek body shape and pointed fins are believed to be adaptations for living in fast water. Flathead chubs grow to about 12 inches in length and are sometimes used as bait. They are often caught by anglers.

Diagnostic Characteristics
Very silvery, shading to brown or dusky on back. Mouth large with a conspicuous barbel at each corner. Pectoral fin sickle shaped with long, sharply pointed tip that may extend almost to front of pelvic fin.

Species Range
Montana Range


Western Hemisphere Range


Range Comments
In Montana, the linear distance of streams and rivers occupied by the flathead chub is between 10,000-20,000 km (6,000-12,500 miles). Linear range was calculated to be a conservative 10,961 km (6850 river miles) of actual documented occupied streams to a more liberal river extent of >12,400 km (8,000 miles) based on MFISH river miles calculations associated with surveys, this was calculated for the Nature Serve Species ranking in 2012.

Observations in Montana Natural Heritage Program Database
Number of Observations: 1886

(Click on the following maps and charts to see full sized version) Map Help and Descriptions
Relative Density



(Observations spanning multiple months or years are excluded from time charts)

Makes spawning run to lower Marias River.

Plains rivers and streams with some to moderate turbidity. Many reaches of prairie streams and rivers have the characteristic riffle/run/pool habitat and gravels preferred by flathead chubs. Studies on middle Missouri River showed it was relatively more abundant in the lower gradient downstream sections.

Food Habits
Eats mostly aquatic invertebrates of all sorts but includes some vegetation. Heavy seasonal use of terrestrial insects.

Were most common in main channel border and side channel chute. Habitat types on middle Missouri River. Commonly found in both riffles and pools.

Reproductive Characteristics
Sexually mature at 2 years. Probably spawns during July. Middle Missouri River study showed spawning from mid June to latter half of July with peak in early July.

  • Additional ReferencesLegend:   View Online Publication
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    • Barfoot, C.A. 1993. Longitudinal distribution of fishes and habitat in Little Beaver Creek, Montana. M.Sc. Thesis. Bozeman, MT: Montana State University. 66 p.
    • Bramblett, R.G. 1996. Habitats and movements of pallid and shovelnose sturgeon in the Yellowstone and Missouri Rivers, Montana and North Dakota. Ph.D. Dissertation. Bozeman, MT: Montana State University. 210 p.
    • Clancey, C.G. 1978. The fish and aquatic invertebrates in Sarpy Creek, Montana. M.Sc. Thesis. Bozeman, MT: Montana State University. 54 p.
    • Craig, V.E. 1952. A story of fish production as it applies to Montana. M.Sc. Thesis. Bozeman, MT: Montana State University. 92 p.
    • Hendricks, P., S. Lenard, D.M. Stagliano, and B.A. Maxell. 2013. Baseline nongame wildlife surveys on the Fort Peck Indian Reservation. Report to the Assiniboine and Sioux Tribes of the Fort Peck Indian Reservation. Montana Natural Heritage Program, Helena, MT. 83 p.
    • Mullen, J.A. 2007. Spatiotemporal variation of fish assemblages in Montana prairie streams. M.Sc. Thesis. Bozeman, MT: Montana State University. 102 p.
    • Mullins, M.S. 1991. Biology and predator use of cisco (Coregonus artedi) in Fort Peck Reservoir, Montana. M.Sc. Thesis. Bozeman, MT: Montana State University. 68 p.
    • Penkal, R.F. 1977. Black bass populations of the Tongue River Reservoir, Montana. M.Sc. Thesis. Bozeman, MT: Montana State University. 111 p.
    • Rosenthal, L.R. 2007. Evaluation of distribution and fish passage in relation to road culverts in two eastern Montana prairie streams. M.Sc. Thesis. Bozeman, MT: Montana State University. 78 p.
    • Sanborn, B.W. 1990. The ecology of Rainbow Trout in the Bighorn River, Montana. M.Sc. Thesis. Bozeman, Montana: Montana State University. 63 p.
    • Stash, S.W. 2001. Distribution, relative abundance, and habitat associations of Milk River fishes related to irrigation diversion dams. M.Sc. Thesis. Bozeman, MT: Montana State University. 82 p.
    • Stevenson, H.R. 1975. The trout fishery of the Bighorn River below Yellowtail Dam, Montana. M.Sc. Thesis. Bozeman, MT: Montana State University. 67 p.
    • Stringer, A.L. 2018. Status of Northern Pearl Dace and chrosomid dace in prairie streams of Montana. M.Sc. Thesis. Bozeman, MT: Montana State University. 150 p.
    • Trenka, R.J. 2000. Community structure and habitat associations of fishes of the lower Tongue and Powder Rivers. M.Sc. Thesis. Bozeman, MT: Montana State University. 85 p.
    • Werdon, S.J. 1992. Population status and characteristics of Macrhybopsis gelida, Platygobio gracilis and Rhinichthys cataractae in the Missouri River Basin. Masters thesis. South Dakota State University, Brookings, SD. 55 pp.
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Citation for data on this website:
Flathead Chub — Platygobio gracilis.  Montana Field Guide.  .  Retrieved on , from