RIVER FISH · Cold western rivers
Mountain whitefish
Prosopium williamsoni
A native western salmonid with a small mouth and silvery body, common in cold rivers and lakes yet often overlooked beside trout.
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Meet the fish
- Habitat
- Clean, cold rivers, streams and lakes; U.S. Fish & Wildlife Service research notes frequent use of larger, low-gradient cold streams.
- On the menu
- Aquatic insects and other bottom-dwelling invertebrates, with feeding often concentrated near the riverbed.
- Size context
- Size varies by river and lake. Colorado's master-angler program uses 15 inches as its qualifying benchmark, not as a typical or legal size.
- Range & local context
- Mountainous areas of western North America from Canada into the western United States.
Living with the river
Water & habitat
Cold water, channel condition and bottom habitat matter. Flow readings can provide context but do not describe the insect community or exact holding water.
Seasonal life
Spawning typically occurs in autumn as water cools, using flowing water and gravel or rubble habitat.
Why this song? Mountain whitefish live in cold western rivers and lakes, so “Mountain Song” fits the landscape behind the fish.
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Before you go
Mountain whitefish are a native game fish in many western waters. Check local limits and special regulations before keeping fish.
Use the linked agencies and the relevant river guide for current regulations, closures and consumption advisories. A species profile is not a fishing license or a statement that harvest is allowed.
Editorial review: . Regional size examples are labeled; maximum lengths are not typical sizes.
More river fish
Keep exploring species connected to the same river-guide network.