The lake chub is one of hundreds of species belonging to the minnow family, one of the largest of all fish families. The lake chub is a northern fish and is common in the northern Rockies, most of Canada west of Hudson Bay, and in the Yukon River system of Alaska. The Black Hills population is considered a relict of the glacial periods. Other relict populations, stranded in isolated habitats, are known in North Dakota, Nebraska, Colorado, and Iowa. Although the lake chub tolerates a wide variety of habitats, it prefers cool streams and lakes.
Lake chubs can be extremely abundant in good habitat and often form large schools.
It is an important forage fish in large northern lakes that often contain few other species of forage fish. Like most minnows, the lake chub is a small fish, rarely attaining a length of more than six inches. Adults are dark brown to green above and pale below, with a dusky lateral stripe that varies from a very distinct marking to an inconspicuous line. Breeding males develop tubercles on the head and the pectoral fin. In addition to the development of tubercles, males also display reddish-orange spots at the base of the pectoral fin and just behind the gill cover.