Rainbow Trout

From 10th Trip: Irvine Lake 1/16/09

More info at http://en.wikipedia.org/wiki/Rainbow_trout

(Oncorhynchus mykiss)

Rainbow trout have very small, fine scales on their torpedo-shaped body. They have silvery sides with a horizontal pinkish band that varies in intensity in different populations. The back is bluish to greenish with black spots on the back and sides. Rainbows have no teeth on the tongue. Rainbow trout belong to the family of fish known as salmon and are characterized by adipose fins and by an axillary process at the base of each pelvic fin. The caudal fin is not forked, and has radiating rows of black spots. There are more than a hundred varieties of rainbow trout, but only three subspecies: the common rainbow; steelhead (or coastal rainbow); and Kamloops rainbow.

Rainbows may live up to 11 years, but the usual life span is four to six years. Growth is highly variable, depending on the habitat. A typical stream-dwelling rainbow grows to weigh about 1 pound (0.5 kg) in four years.


Rainbow trout are native only to the Pacific slope of North America, but have been widely introduced on every continent, except Antarctica.Rainbow trout prefer cool, clear streams and lakes, but can survive in lakes or ponds on the prairie, as long as there is cool, oxygenated water in the depths. Rainbows prefer water from 55 to 60 F, and will tolerate temperatures up to 75 F.
Natural History

The diet consists mainly of immature and adult insects, plankton, crustaceans, fish eggs, and small fishes. Rainbows consume far fewer fish than do brown trout.

In the wild, most varieties of rainbows spawn in the spring, however, spawning may occur anytime of the year. Spawning takes place in small tributaries, often at the inlet or outlet of a lake, where water temperatures reach 50 to 60 F (10-16 C). The spawning site is usually the tail of a pool, or the riffle at the head of a pool, where gravel bars have ample oxygen-rich water, and no suffocating silt. Before spawning, males undergo astounding anatomical changes. A male’s jaws lengthen and the lower jaw develops a kype . All fish become darker when in spawning condition. Their spots become more prominent and the pink stripe more intense.

The female digs several redds for depositing the eggs. She turns on her side and beats her tail against the bottom, moving the gravel away to create a depression longer than her body and about half as deep. As the female digs, she is often accompanied by more than one male. The largest male is dominant and defends his territory by charging the smaller ones, using his kype to nip them. The male and female lie side by side and release milt and eggs. Sometimes the other males also deposit milt in the redd .

About the Author

Sean loves to fish in Southern California and this site is his journal of his adventures in fishing. He started fishing when he was a little guy with his dad David, and has continued to this day with his family. In his day job, Sean has been a graphic designer for over 15 years, designing everything from in-store displays and signage for supermarkets to e-commerce auction sites for an online consumer electronics company. He was a web and graphic designer then later an art director for McMullen Argus Publishing (Primedia), building and working on sites for Lowrider Magazine and Super Chevy, plus 30 other automotive magazine sites. Sean seized the opportunity to teach other aspiring designers - a passion that took him first to Learning Tree University and then to Golden West College in Huntington Beach, CA, where he has been an integral part of the renowned digital arts department for more than ten years. Throughout his teaching career, Sean maintained a freelance business, designing for clients including the Academy of Television Arts & Sciences (Los Angeles Area Emmy Awards), Image Comics and many more. See his work at http://www.glumace.com.