Onorhynchus mykiss is well known for its ability to adapt to different conditions. It is a member of the Salmonidae family and native to the eastern Pacific where it is found from Alaska to Mexico. It is now in every Canadian province and was first introduced to Nova Scotian waters in 1899. The size of the rainbow trout varies, but in Atlantic Canada, the average weight is 0.5-1 kilograms. It has a long, slender body, with an iridescent band running along each side from head to tail. The overall body color can range from bluish to yellow-green, brown or black.

Farming Life Cycle:

The cycle begins with harvesting eggs from selectively bred spawners. Once the eggs are fertilized, they are placed in tanks for hatching. After they hatch, they are called sac-fry and remain in the tanks, living off the energy reserves in the yolk sac, which is attached to the belly. After four to six weeks, the fish are fed commercial food. Soon the fry grow and reach the fingerling stage. They are fed a special diet and grow until they are big enough to be harvested. It usually takes the trout between 12 and 18 months to reach market size. The harvest size is generally 284-397 grams (10-14 ounces), commonly referred to as "pan-sized." Rainbow trout products are sold fresh whole, as fillets and smoked.

Feeding Habits:

In fish farms, rainbow trout are fed food pellets. The pellets contain 80% fish meal and fish oil with minerals and vitamins added. Their diet is similar to the salmon diet. This provides proper nutritional balance geared toward growth and product quality.

Growing Techniques:

First, eggs are placed in incubators where the rate of growth is controlled mainly by water temperature. There are a number of incubator units, including troughs, combi-tanks, stacked tray units, jars and baskets. After hatching, the fry are fed in troughs or small, circular units where they are reared to a 1-5 gram (0.04-0.2 ounce) size. Next, they are transferred to rearing units. A number of methods are then used for final grow-out. The facilities may include earthen ponds, cages in ponds, rectangular or circular tanks or concrete raceways.

Farming Areas:

There are numerous hatcheries and grow-out ponds in Nova Scotia. Hatcheries and grow-out sites must have adequate water supplies to be successful. These operations supply rainbow trout for U-fish or retail markets, as well as seed stock for marine grow-out sites.

See also Steelhead Salmon.

Conclusion:

For more information, contact Aquaculture (aquaculture@gov.ns.ca).

Nova Scotia Fisheries and Aquaculture
P.O. Box 2223
Halifax, Nova Scotia
Canada B3J 3C4

Phone: (902) 424-0356
Fax: (902) 424-4671