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NATURAL HISTORY

LEAST CHUB } Lotichthys phlegethontis
FAMILY: Cyprinidae

DESCRIPTION: The least chub is a colorful minnow measuring less than two-and-a-half inches in length. Males are olive-green above, steely blue on the sides, with a golden stripe behind their gill openings; mature males develop a lateral red stripe during spawning season. Females are similar in color with a more subtle gold coloration than their male counterparts and distinctive silvery eyes. Least chub have fins ranging in hue from watery white to amber.

HABITAT: These fish are found in freshwater springs, ponds, marshes, and streams. They have a broad tolerance in terms of water quality, yet they prefer somewhat shallow pools with moderate to dense vegetation and minimal current. The presence of aquatic vegetation — especially bulrushes, sedges, duckweed, watercress, algae, and cattails — is important, as the species depends on algae and other plants for food, shelter, and oxygen.

RANGE: Least chub have persisted in the remaining wetland pockets left by the receding Lake Bonneville and Lake Provo in western Utah. In the 1800s, least chub were described as common near the Great Salt Lake, in Utah Lake, Beaver River, Provo River, Little Salt Lake, in tributaries of the Sevier River, and several springs in the Snake Valley. The species’ current distribution is limited to six wild populations in the Utah west desert, Wasatch Front, and the Sevier River.

MIGRATION: Seasonal water-quality changes lead least chub to move back and forth between different habitat types, especially between springs and marshes.

BREEDING: Spawning takes place in the spring; exact timing depends on environmental conditions. Least chub find their way to nearby marshes for spawning, where aquatic vegetation provides important habitat for eggs. Females first reproduce around one year of age and mate with one or more males per breeding season. Eggs are released gradually over an extended period, and a single female can produce anywhere from 300 to 2,700 in a given year.

LIFE CYCLE: Least chub can live up to six years. They have been known to live significantly longer in the wild than in captivity.

FEEDING: Least chub are opportunistic feeders and have varied diets made up mostly of insects, crustaceans, and algae, in that order.

THREATS: The main threats to least chub are urbanization, water development, livestock grazing, and competition from nonnative species. The Snake Valley, the area today considered to be the chub’s “stronghold,” is at risk from groundwater pumping to feed the booming human population of southern Nevada.

POPULATION TREND: The species was once common throughout the Bonneville basin, with more than 50 recorded occurrences. The decline of the species was first noted in the 1940s. By 1996, local extirpations in many areas where this fish was once abundant pushed it toward the brink of extinction, with only six remaining wild populations intact.

Photo courtesy of USFWS