Truite arc-en-ciel
Rainbow trout "(Oncorhynchus mykiss)", native to Pacific Ocean tributaries in North American and Asia was first introduced into the Gibbon River, above and below Gibbon Falls in 1890. In 1923, Rainbow trout were introduced into the Firehole River above Firehole Falls. Rainbow trout have also been introduced into a number of Yellowstone lakes. They exist in the Yellowstone River below Yellowstone Falls and in the upper Slough Creek drainage.