The most widely distributed fish in the region is the rainbow trout, which is found in all 23 major drainage basins; however, it is only native to 13 of these. The most widespread native fish is the mountain whitefish, which can be found in 20 of 23 drainage basins. Other fish found in the rivers and streams of the Y2Y region include several species of charr, trout, Pacific salmon, and whitefish, as well as grayling, smallmouth and largemouth bass, perch, walleye, bluegill, shiners, sculpin, dace, minnows, and suckers.

In all, 152 fish species have been identified in the region. Of those, 104 are (or were) native, and 48 are non-native. Five native species have been extirpated from the area, while two have gone fully extinct.

Click here to download a listing of scientific and common names of the fishes of Yellowstone to Yukon drainages.