Common Fish Species of Northwestern Ontario





Osmerus mordax
Rainbow Smelt



Distinguishing Features - Coloration: silvery with pale green back iridescent purple, blue, and pink on sides; white belly. Body: slender and cylindrical; gill rakers long and slender, numbering 26-35; dorsal fin of 8-11 rays; anal fin of 12-16 rays; pectoral fins of 11-14 rays; pelvic fins of 8 rays; has adipose fin; tail fin deeply forked; cycloid scales; lateral line incomplete, with 62-72 scales. Head: elongated and pointed snout mouth large, with protruding lower jaw teeth on both mandibles.

Size - Average Weight - 85 g (3 oz.); average length - 17.75 - 23 cm (7 - 9 in.).


An introduced species to Great Lakes and other inland waters; usually found in dark, cool depths offshore; spawns in spring, in streams, principally during darkness. Female can produce 12,000 to 50,000 eggs, which sink to the bottom and become attached to gravel; eggs hatch rapidly and larval young drift downstream to deep waters.


Smelt feed primarily on crustaceans and small fish, but also eat aquatic and terrestrial insects. The species poses a potential threat to the fishes of our northern lakes. Although it was introduced as a forage fish for larger species, such as Walleye and Lake Trout, it is a voracious feeder upon the young of these and other native fish.

In Lake Superior, however, they were welcomed both as a forage fish and as a recreational target during their spring spawning runs. Systematic harvesting began in 1952, and dip-netting and seining in spawning streams has developed into a popular, seasonal sport. The spring smelt run has become a North Shore tradition.

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