Finfish Breeding and Hatchery Management

Unit 8 - Breeding of trouts

8.2. Habitat and biology of rainbow trout

• The rainbow trout (RBT) is native to North America.
• Since 1874, the RBT has been introduced into several Continents, except Antarctica. It is farmed in about 64 countries.
• It is a hardy fish,
• Easy to spawn
• Fast-growing, reaching 5-10 kg in 3 years, with anadromous (steelhead trout) growing faster (7-10 kg)
• Tolerant to a wide range of environments and handling
• Large-scale fry production is possible as they prefer to feed on zooplankton
• It is anadromous as well as purely river or lake resident (spends entire life in river or lake)
• Can tolerate temperature of 0-27^oC, spawning and growth occur at 9-14^oC.

Identifying characters

• Trouts have fusiform body with 60-66 vertebrae, 3-4 dorsal spines, 10-12 dorsal soft rays, 3-4 anal spines, 8-12 anal soft rays, 19 caudal rays.
• Adipose fin present, usually with black edge.
• Coloration blue to olive green above a pink band along the lateral line and silvery below.

Food and feeding

• Adults feed on aquatic and terrestrial insects, molluscs, crustaceans, fish eggs, minnows and small fishes.
• Juveniles are omnivorous.
• Freshwater shrimps when fed to trouts supply carotenoid pigments which imparts orange color.

Rainbow Trout