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Couesius plumbeus (Agassiz, 1850)
Lake Chub
Family: Cyprinidae
Introduction to the Fish

Photograph

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Map


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Source: Distribution map provided by Don McPhail for E-Fauna BC

Species Information

Dorsal spines (total): 0; Dorsal soft rays (total): 8; Anal spines: 0; Anal soft rays: 7 - 9; Vertebrae: 39 - 44. Distinguished by the spineless fins, normal jaws, and tiny barbel at the corner of the mouth (Ref. 27547). Gill rakers short (Ref. 27547). Caudal moderately forked, with rounded lobes (Ref. 27547). Brown to greenish above, silvery below; a rather indistinct dark or lead-colored band is present along the sides, often extending forward onto the head of small specimens; lower sides and belly often have fine dots of dark pigment (Ref. 27547). In some populations, breeding males develop bright orange-red patches on sides of head and at bases of pectoral fins, but the presence of this color varies from place to place (Ref. 27547).

Source: FishBase. Page, L.M. and B.M. Burr 1991 A field guide to freshwater fishes of North America north of Mexico. Houghton Mifflin Company, Boston. 432 p.

Identification and Subspecies Information

In BC, we recognize an ecotype of this species: Couesius plumbeus pop. 1 (Lake Chub hotsprings ecotype). Please check the BC Species and Ecosystems Explorer for current status designation of Couesius plumbeus - hotsprings ecotype.

Biology

Species Biology

habits virtually any body of water, standing or flowing, large or small (Ref. 5723). Most common in gravel-bottom pools and runs of streams and along rocky lake margins (Ref. 5723). Mostly in shallow water, but may move to deeper parts of lakes during hot weather (Ref. 27547). Feeds on zooplankton, algae, terrestrial and aquatic insects, and small fishes (Ref. 1998

Source: FishBase. Page, L.M. and B.M. Burr 1991 A field guide to freshwater fishes of North America north of Mexico. Houghton Mifflin Company, Boston. 432 p.

Distribution

BC Distribution and Notes

This is the most cold adapted minnow in North America. In northern B.C. there are hints that its reproductive cycle and thermal physiology are worth a closer look, especially in the outlets of hotsprings. The southern edge of the species’ range closely corresponds to the southern margin of glaciation. Most of the B.C. populations in the south are now extinct. It is not clear why they disappeared, although many of the small lakes in this area were “rehabilitated” in the 1950s and 60s. This species is now under study.

Source: Information provided by Don McPhail for E-Fauna BC.
Global Distribution

North America: Alaska (Yukon River drainage). Throughout most of Canada and northern USA; south to Delaware River in New York, south end of Lake Michigan, Illinois, Platte River system in Colorado, and Columbia River drainage in Washington, USA. Relict population in Mississippi River basin in Iowa, USA. Sometimes hybridizes with Rhinichthys cataractae in Lake Superior (Ref. 4564).

Source: FishBase. Page, L.M. and B.M. Burr 1991 A field guide to freshwater fishes of North America north of Mexico. Houghton Mifflin Company, Boston. 432 p.
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Status Information

Scientific NameOrigin StatusProvincial StatusBC List
(Red Blue List)		COSEWIC
Couesius plumbeusNativeS5YellowDD
Couesius plumbeus - hotsprings ecotypeNativeS2RedNot Listed



BC Ministry of Environment: BC Species and Ecosystems Explorer--the authoritative source for conservation information in British Columbia.

Additional Range and Status Information Links

NatureServe Explorer
 University of Alaska Museum

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