Chalk Spring Rainbow

Typical rod-caught rainbow

The Rainbow Trout (Oncorhynchus mykiss) is a native of North America that has been introduced to the UK. It is both farmed for human consumption and stocked as a sporting fish for anglers. Formerly known to science as Salmo gardneiri. Rainbow trout are easily distinguished from brown trout as they have many small black spots but no red spots on the body, and unlike brown trout have small black spots on the tail. The most distinctive feature is the broad iridescent reddish lateral band. In their native N America some strains (Steelhead) are anadromous.

21 lb Rainbow

Life cycleEdit

Like salmon, steelhead are anadromous: they return to their original hatching ground to spawn. Similar to Atlantic salmon, but unlike their Pacific Oncorhynchus salmonid kin, steelhead are iteroparous (able to spawn several times, each time separated by months) and make several spawning trips between fresh and salt water. The steelhead smolts (immature or young fish) remain in the river for about a year before heading to sea, whereas salmon typically return to the seas as smolts. Different steelhead populations migrate upriver at different times of the year. "Summer-run steelhead" migrate between May and October, before their reproductive organs are fully mature. They mature in freshwater before spawning in the spring. The maximum recorded life-span for a rainbow trout is 11 years.


Rainbow trout are predators with a varied diet, and will eat nearly anything they can grab. Their image as a selective eater is only a legend. Rainbows are not quite as piscivorous or aggressive as Brown Trout or Char. Young rainbows survive on insects, fish eggs, smaller fish (up to 1/3 of their length), along with crayfish and other crustaceans. As they grow, though, the proportion of fish increases in most all populations. Some lake dwelling lines may become planktonic feeders. While in flowing waters populated with salmonids, trout eat varied fish eggs, including salmon as well as the eggs of other rainbow trout, alevin, fry, smolt and even left-over carcasses.