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Montana Field Guide

Montana Field Guides

Lake Chub - Couesius plumbeus

Native Species

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

Agency Status


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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 lake chub is a native minnow found in Montana's eastern and northern drainages. They are an indicator species of the core prairie fish assemblage found in the Perennial Prairie Stream Aquatic Ecological System. Lake chubs are usually 6 inches or less in length (can be confused with creek chubs in the southern part of their MT range), and are reported to be an important forage fish in some locations. Lake chubs generally prefer small, slow streams and have been illegally introduced in several mountain lakes.

Diagnostic Characteristics
Silver gray overall, dusky on back, underside whitish. A midside band is present but often indistinct. Scattered dark scales may be present, giving a speckled appearance. Breeding males develop reddish patches, particularly on the pectoral fin bases. A well-developed, rounded barbel is located slightly above each corner of the mouth.

Species Range
Montana Range


Western Hemisphere Range


Observations in Montana Natural Heritage Program Database
Number of Observations: 913

(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)

Runs out of lakes up to a mile or more to spawn in streams.

Favors creek type habitat, mostly at lower elevations, and is rarely found in the larger streams. Also in some mountain lakes.

Food Habits
Feeds on plankton and small aquatic invertebrates

May cross with longnose dace. No hybrids reported in Montana.

Reproductive Characteristics
Most are sexually mature at 3 yrs. Spawns mid May - mid June when water temps. reach 50 degrees F. No parental care. Eggs hatch in 10 days at 56 degrees F.

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Citation for data on this website:
Lake Chub — Couesius plumbeus.  Montana Field Guide.  .  Retrieved on , from