A rainbow of a fish

The rainbow trout is one of the most beautiful and most widely distributed freshwater fish in all the world.

It now thrives in the wild cold-water streams of all continents except Antarctica. This extensive distribution is not because the rainbow trout has supernatural powers. Man has introduced it into waters far outside its native range of Pacific Ocean tributaries of western North America and Asia.

Intended as a human food source and also for sport fishing, when introduced and established in new places such as New Zealand, South America and Australia, the rainbow trout has caused damage to native fish species. In some instances, rainbow trout have decimated native frog species by feeding on frog eggs, tadpoles and small frogs. Rainbow trout have been introduced into the limited freshwater streams of some of the Hawaiian Islands, where it is now considered an invasive species.

In fact, the beautiful and much loved rainbow trout has been put on the list with the world's top 100 invasive species of living things.

The rainbow trout is a relative of the steelhead trout. I recently took this rainbow trout photo as the fish swam in a clear, cold stream in southwest Missouri. I estimated it to be 2 1/2 to 3 pounds and about 18 inches long.