The species is a slender, silvery-coloured minnow with a large mouth and transparent fins; it averages 51 to 76 mm in length. Its name comes from the bright red colour that appears on the head and pectoral fins of the breeding male. On females, the red hue, if it develops, is paler. Breeding males also develop 100 or more small, rounded swellings that occur primarily on the snout, lower jaw and anterior pectoral; and sometimes on the upper surfaces of the pelvic, dorsal and anal fins. Similar swellings, or tubercles, may appear on the heads of females. The species is closely related to both Emerald and Silver Shiners. The body of the Emerald Shiner is deeper and more compressed, and its snout is blunt and shorter. The Silver Shiner has a prominent stripe on its mid-back, nine pelvic rays and dark crescents between its nostrils. The dorsal fin of the Silver Shiner is also set closer to the front compared with the Carmine Shiner.
Distribution and Population
The Carmine Shiner is found in south central western Manitoba. It is rare in Manitoba but has occurred in the province over a long time. It has been recorded in the Whitemouth-Birch river systems, and it may also occur in the Red River in southern Manitoba.
The Carmine Shiner prefers clear, fast-flowing larger streams and small rivers with clean gravel bottoms. It is often found in schools in riffles (shallow parts of streams where water flows brokenly). It also occurs in clear pools in the lower portions of streams near where they join with larger streams or rivers; an area in which aquatic insects are plentiful. The species cannot tolerate turbid or silty water. Silt-free pools and water temperatures of at least 21 °C seem to be critical for spawning activity in New York State.