The Greenback Cutthroat Trout was adopted as the official state fish on March 15, 1994. The Rainbow Trout was considered the state fish from 1954 until 1994. However, it was never officially adopted.
The Greenback Cutthroat Trout lived in small creeks, streams, and rivers throughout Colorado. As mining and human occupation expanded, the greenback populated died off due to pollution and to competition from other species of trout.
Up until the late 1980s biologists feared the fish was extinct. However, researchers in the early 1990s discovered small populations of the greenback in a remote streams in Rocky Mountain National Park. Colorado Division of Wildlife and National Park personnel took immediate steps to protect and propagate the greenback. Plans have been made to reintroduce this colorful fish to other waters within the state.