Rainbow Trout (Oncorhynchus mykiss)

Rainbow trout possess a small head and a long body. Related to the brown and brook trout, rainbows have two dorsal fins, the smallest of which is composed of adipose tissue. Rainbows display a bright blue or green flush on their backs, and a silver-white shimmer on their bellies. The middle of each side of the fish exhibits a distinctive longitudinal red stripe. This coloration is typical of the species, but may vary from one trout to another and even disappear in some fish, particularly sea-run rainbow/steelhead.

There is a distinct color variability as rainbow trout near the spawning season. Mature rainbows in particular display a darker and brighter pigmentation. Rainbows are speckled with little dark spots that extend from their tail and fins to their head, particularly above the longitudinal red side stripes.

Rainbow trout are found in almost every river in Chile's Patagonia region and in many of the lakes. Rainbow trout are esteemed by anglers for their combativeness, aerobatics and size. They reach as much 22 pounds in lake environments. They feed primarily on insects, mollusks, crustaceans and fish and readily take dry flies, terrestrials, streamers and nymphs.

Some interesting trivia about rainbow trout habitat:

  • The optimum temperature for the rainbow trout to flourish and grow is between 56° to 70° F. At temperatures above 70° F, rainbows become sluggish and inactive.
  • The minimum amount of dissolved oxygen in the water required by rainbow trout to survive is 5 to 6 parts per million. Rainbows thrive in highly oxygenated waters, from 9 to 11 parts per million.
  • Alkalinity (pH) is another important factor. The adequate range is a pH of 7 to 8. Rainbow trout will not reproduce in an acidic environment (waters with a pH of 6 or lower).
  • Rainbow trout are sensitive to color. Rainbows, browns and brook trout perceive some colors in spectrums which are invisible to humans. Red is one of the colors they perceive more intensely.
  • Rainbow, brown and brook trout are often found deep in the bottom of holes, under banks, or lily pads. On a bright sunny day, cast to these areas and to the shady sides of rocks.