Flathead Chub - Platygobio gracilis
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.
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.
Western Hemisphere Range
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.
Summary of Observations Submitted for Montana
Number of Observations:
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(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.
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.
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.
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- 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.