ABSTRACT
The rainbow trout (Oncorhynchus mykiss) is a trout and species of salmonid native to coldwater tributaries of the Pacific Ocean in Asia and North America. Freshwater forms that have been introduced into the Great Lakes and migrate into tributaries to spawn are also called steelhead. Rainbow Oncorhynchus mykiss trout likes to live in cold water and are mostly found in lake, reservoirs, rivers, etc., and rainbow trout are also considered as fluvial populations in the whole forest. The population of fluvial of rainbow trout is not figured out clearly because they do not refer to the migration into rivers to spawn lives into larger drainage. Female partner prefers to make their nest where male partner protects it from other interested males and predators. The 260female digs the nest (a redd) by using her anal fin and then descends sits in a way so that her vent and anal fin goes into the deepest part of the redd. The male partner joins her parallelly so that their vents become opposite to one another. Both the partners open their mouth, arch their backs, and deposit the eggs and milt (fish sperm) at the same time. The eggs are enclosed by a cloud and the fertilized. However, the reproductive processes of the Rainbow trout are affected by various environmental factors and changes the internal endocrine environment of the fish. Therefore, Rainbow trout, has received wide research consideration. This chapter summarized the reproductive patterns of Rainbow trout and impact of environmental and hormonal stress on the reproduction of Rainbow trout.
