Castostomus platyrhynchus

Identification Tips:

•Mouth on bottom of head.
•Mouth has a shallow cleft between the lower lips, a deep notch at each corner, and a hardened sheath on the lower jaw.
•Dorsal fin: 10-12 rays

Conservation Status:

British ColumbiaCanadaNatureserve
COSEWICSpecies at Risk Act
Blue ListSpecial ConcernSpecial ConcernG5, S2S3

Information Source: BC Conservation Data Centre:

Life History:

•A very specialized feeder; scrapes algae and aquatic invertebrates from rocks using its chisel-like lower jaw
•Maximum size approximately 25 cm
•Probably a different species than the Mountain Suckers east of the Rockies.
•Nothing is known about its biology in B.C.


•Found in various river habitats with rocky bottoms.
•Occasionally in Lakes (outside of BC)


British Columbia
•A scattered distribution; Fraser River between Hope and Chilliwack, North Thompson River near Heffley, Similkameen River near Keremeos, and possibly in Salmo River (Kootenays)

•In the west, from Sacramento River in California north to southern BC
•East of the Rocky Mountains (likely a different species) it occurs from Saskatchewan and Alberta through the Missouri River system

Primary Information Source:
McPhail, J.D. 2007. The Freshwater Fishes of British Columbia. University of Alberta Press. Edmonton, Alberta.