From the very first time a fishing guide from Minturn Anglers in Denver introduced me to rainbow trout fly fishing on the Dream Stream, a segment of the South Platte River in Colorado, I have been captivated by this magnificent fish. It’s hard to beat the experience of watching one of these hard fighting beauties leaping into the air at the end of my line. Wanting to learn more about them seems a natural thing to do.
Spawning time for rainbow trout in Colorado begins about mid-March. Migrating upstream, often many miles, they will dig small depressions in riverbed gravel. Female trout clean debris away from these redds, as they are called, and then lay eggs in these nests. These eggs are fertilized by the male trout, covered by more gravel are remain there until they hatch four to seven weeks later.
Their growth cycle is amazing. These newly hatched trout are called sac fry or alevin, and for their first two weeks survive on the yolk sac which surrounds them. They then begin feeding on zooplankton. These fry grow and into what are called parr, because they develop “parr” marks or vertical marks on their sides. As parr become stronger, they move into more active parts of the stream where they eat insects and small animals that fall into or live in the water. These fry grow to fingerling size, from 3 to 9 inches.
An adult rainbow trout averages between 1 to 5 pounds, and sometimes even to 20 pounds. They have a reddish broad stripe from their gills to the tail, and are generally blue-green or olive green, with small black spots over the entire body.
Rainbow trout tend to eat almost everything available to them, from small insects to crayfish, leeches snails and fish eggs. Their willingness to rise to a variety of lures and baits, along with their aggressive and combative nature, make them a popular target for all fly fishing anglers. Once you have tagged your first, you will know why rainbow trout are considered one of the five top sport fish in North America!