Rainbow trout have the typical trout-shape with an adipose fin, and a squarish tail that has black spots throughout. The rainbow trout has 10-12 anal rays and a white mouth and gums. Adult freshwater stream rainbow trout average between 0.5 and 2.3 kg, while lake-dwelling and anadromous forms may reach 9.1 kg. Coloration varies widely based on subspecies, forms and habitat.
Adult fish are distinguished by a broad reddish stripe along the lateral line, from gills to the tail, which is most vivid in breeding males. Wild-caught and hatchery-reared forms of this species have been transplanted and introduced for food or sport in at least 45 countries and every continent except Antarctica.
Adult fish have a broad reddish stripe along the lateral line, from gills to the tail, which is most pronounced in breeding males.
Golden trout, cutthroat trout.
Rainbow trout generally spawn in early to late spring (January to June in the Northern Hemisphere and September to November in the Southern Hemisphere). The maximum recorded lifespan for a rainbow trout is 11 years.
Rainbow trout are mainly meat eating fish. They feed on a wide variety of prey including insects, crustaceans, mollusks, fish and fish eggs.
Habitat and range
Rainbows are considered fastwater fish, preferring the swift runs and riffle areas of streams. They may live in small creeks, as well as suitable spots in large rivers, the tailwaters of dams, and in lakes and reservoirs. As trout, rainbows live in cold, clean, well-oxygenated water. This sought after species are found throughout parts of southern Africa but prefers the highlands of Mpumalanga, eastern – and western Cape.
Rainbow trout are predators with a varied diet and will eat nearly anything they can capture. They are not as piscivorous or aggressive as brown trout or chars. Rainbow trout in fresh water, routinely feed on larval, pupal and adult forms of aquatic insects (typically caddisflies, stoneflies, mayflies and aquatic diptera). They also eat fish eggs and adult forms of terrestrial insects (typically ants, beetles, grasshoppers and crickets) that fall into the water. Other prey include small fish up to one-third of their length, crayfish, shrimp, and other crustaceans. As rainbow trout grow, the proportion of fish consumed increases in most populations. Some lake-dwelling forms may become planktonic feeders. In rivers and streams populated with other salmonid species, rainbow trout eat varied fish eggs, including those of salmon, brown and cutthroat trout and the eggs of other rainbow trout. Rainbows also consume decomposing flesh from carcasses of other fish.