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National Factsheet - Rainbow Trout

General Description

The rainbow trout is a member of the salmon family of fishes and has the following characteristics:

• an elongate, laterally compressed body;
• a rounded snout, which becomes extended and the lower jaw turns up in breeding males;
• the back, upper sides and the top of the head are steel blue, blue-green, yellow-green to almost brown;
• the sides are silvery, white or pale yellow-green to grey, and marked with a pink blush to red band and many small black spots;
• the underside is silvery, white or grey to yellowish;
• the dorsal and caudal fins have radiating rows of black spots, while the remaining fins are buff with few spots; and stream dwelling and spawning brown trout display darker, more intense colours, whereas lake residents are lighter, brighter and more silvery.

Distribution

The rainbow trout is one of the most widely introduced fishes on a global basis. Its native range was the eastern Pacific Ocean and the freshwater west of the Rocky Mountains, from northwest Mexico to Alaska. In Canada, the rainbow trout occurs outside British Columbia from the Avalon Peninsula of Newfoundland, across the southern portions of the provinces from Nova Scotia to Ontario, north to central Manitoba, to northern Alberta, and in the Yukon.

Habitat and Life History

The rainbow trout is a cold-water fish species. The habitat of stream-dwelling rainbow trout is usually small to moderately large, shallow rivers with moderate flow and gravel bottoms, of the pool-riffle type. The lake-resident trout are usually found in moderately deep, cool lakes with adequate shallows and vegetation for good food production. For a lake population to be self-sustaining, there must be a gravelly river to which the adults can migrate during the spawning season.

Rainbow trout spawn in the spring immediately after the ice melts. The usual spawning site chosen is a bed of fine gravel in a riffle above a pool. The female digs a redd (nest) in the gravel by turning on her side and beating her tail up and down. During spawning, the eggs fall into spaces between the gravel and immediately the female begins digging at the upstream edge of the nest covering the eggs with the displaced gravel. The eggs usually hatch in approximately 4 - 7 weeks; however, the time of hatching varies greatly with region and habitat. The fry commence feeding about 15 days after hatching and their diet consists mainly of zooplankton. The growth rate of rainbow trout is variable with area, habitat, life history and quality and quantity of food.

Food Habits

The rainbow trout generally feeds close to the bottom of its habitat. Adults are predaceous and feed on aquatic and terrestrial insects, molluscs, crustaceans, fish eggs, minnows and other small fishes.

Economic Importance

The rainbow trout is one of the top five sport fishes in North America, and it supports a cottage fish farming industry in the three Prairie Provinces.

The rainbow trout is an excellent food fish, which is marketed fresh and frozen.

Fishing Facts

The stock of rainbow trout originally introduced to the Great Lakes in 1895 was the steelhead.

Further Information

Referrals Coordinator
Ontario-Great Lakes Area
Fish Habitat Management Program
Fisheries and Oceans Canada
867 Lakeshore Road
Burlington, ON L7R 4A6
Telephone (905) 336-4595
referralsontario@dfo-mpo.gc.ca