Photo by Nathaniel Skousen ©
Physical Characteristics

Colors vary greatly-with patterns depending on habitat, size and maturity. Stream residents and migrant spawners are darker and have more intense colors than lake residents or non-spawners. Lake residents tend to be silvery with subdued colors. A mature rainbow is dark green to bluish on the back with silvery sides. The pinkish to reddish horizontal band typifies the species. The belly may be white to silvery. Irregular and profuse black spots are usually present on the head, back and sides. The pelvic and anal fins are translucent pink to gray-green and tipped in white. Rainbow trout also tend to have a fairly blunt snout. Rainbows range from 12 to 36 inches in length.

Habitat and Range

Rainbows and steelhead occur in well-oxygenated lakes and streams where the temperature normally doesn't rise above 12 degrees C in summer.

Feeding

Rainbow trout have a varied diet. They are predators, eating any smaller fish from nearly the time they are born. Insects make up a large portion of the diet, along with crayfish and other crustaceans, some lake dwelling species may become planktonic feeders. Trout of all ages will eat nearly anything they can grab, in contrast with the legendary, selective image people often have of the animal's nutrition habits. They are near the top of the food chain in most freshwater environments. However, they are lower on the rung of other freshwater predators such as pike, muskie, lake trout, and chinook salmon. Rainbows will take fish up to and over 1/3 of their length. However they are not quite as piscivorous or aggressive as the brown trout or lake trout, which is actually a char. The rule of thumb is that rainbows consume more fish and fewer insects as they grow, but insects continue to be a part of the diet in most all populations.

Breeding and Spawning

Like salmon, steelhead are anadromous: they return to their original hatching ground to spawn. Unlike salmon, which die after spawning, steelhead rejuvenate after spawning so they may return to the oceans to start the anadromous cycle once again. The steelhead smolts (immature or young fish) usually remain in the river for about a year before heading to sea, whereas salmon typically return to the seas as smolts. Different populations of steelheads 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. "Winter-run steelhead" mature fully in the ocean before migrating, between November and April, and spawn shortly after returning. Similar to Atlantic salmon, but unlike their Pacific Oncorhynchus kin, steelhead are iteroparous and may make several spawning trips between fresh and salt water.