Rainbow trout live in brackish, fresh or marine waters of temperate zones. Anadromous trout, develops and reproduces early in freshwater streams and then migrates to the ocean where he will spend his adult life. When they are in fresh water they are located at temperatures up to 24-25 ºC. Those that are not anadromous remain in fresh rivers or streams, near areas with vegetation that facilitate shade.
The Oncorhynchus mykiss species needs burdensome beds to deposit its eggs, they are sensitive to the conditions that fill them with sediments or the cleaning of channels in which it lives. Juvenile trouts are found in calm waters, since they can die in too fast courses.