Prosopium Williamsoni



Freshwater Rivers, Lakes, Streams

3 - 5 pounds

10" - 28"

Mountain Whitefish

Also Known As: Rocky Mountain Whitefish, Mister White

Mountain Whitefish (Prosopium Williamsoni) Fish Description

This mountain whitefish is predominantly found in streams, but numbers have also been observed in reservoirs and lakes. Their population grows the most in clear and cold temperature rivers in the northwest area of North America, and usually co-habitat with trout.

Typically, this fish has a columnar shape with large scales and has a bronze-white or greenish-white color. Their needle-like snouts and narrow but rounded mouths make them competent in slurping up invertebrates and zooplankton from the bed’s bottom.


Interesting Facts About the Mountain Whitefish

  • Considered by some trout anglers as a “trash fish,” because they catch mountain whitefish instead of trout.
  • The Mountain Whitefish can reach up to 15,000 fish per mile in the Madison River. 
  • They can be cooked, smoked, or pickled.
  • It can live up to 18 years.


Mountain Whitefish Diet and Size

The mountain whitefish’s feeding peaks during the winter seasons, and consists mostly of bottom-dwelling aquatic insects. This carnivorous fish has been known to feed on terrestrial insects, smaller fish, and even fish eggs.

Mountain whitefish can weigh up to 5 pounds and grow to about 10-16 inches. While this small fish does not normally grow greater than 20 inches, the world record caught from the Columbia River in 1983, weighed 5 pounds and 2 ounces. 


Mountain Whitefish Habitat & Distribution 

The habitat range of the mountain whitefish stretches from the McKenzie River in Canada’s Northwest Territories to the Green River basin Utah. They can also be found in the drainages of some Pacific coastal rivers of Briti