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Species Index Game and Fish Home

Mountain whitefish
Prosopium williamsoni
Identifying Characteristics

Small pointed mouth
Adipose fin
Distinguished from trout by larger scales
Distinguished from grayling by the small, pointed mouth and smaller dorsal fin
Distinguished from suckers by the presence of the adipose fin
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Other Information
In Wyoming, the mountain whitefish is common in all drainages west of the Continental Divide. It also occurs in the Madison, Yellowstone, Bighorn and Tongue drainages in the Missouri Basin. Although it inhabits some lakes, the mountain whitefish is generally found in large, clear streams where it prefers deep, fast water.

In streams, the whitefish feeds mainly on insects, including caddis fly and midge larvae, and stonefly and mayfly nymphs. Plankton is the primary food in lakes. The whitefish is a fall spawner, with the spawning period generally beginning in mid-October.

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Angling Tips
Whitefish are often easily caught. Small nymphs, dry flies, and spinners are excellent baits, as are aquatic insects fished on a small hook. Whitefish are good fighters when taken on light tackle; they are excellent table fare as well, especially when smoked.

Wyoming whitefish generally average 10 to 16 inches in length.

Mountain whitefish image