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Mountain Whitefish

Mountain Whitefish

Mountain Whitefish are native salmonids widely distributed throughout Idaho's cold, clean rivers and lakes. They're one of the most abundant game fish in Idaho, particularly in larger streams and rivers of the Snake River and Columbia River systems.

Scientific Name: Prosopium williamsoni

Physical Characteristics:
  • These silvery fish are distinguished by their large scales (74-90 on lateral line), small ventral mouth, prominent adipose fin, and trout-like appearance, typically reaching 10-16 inches with some specimens exceeding 20 inches.
  • Look for their glittery, 'disco ball' appearance underwater.

What to know

Habitat Distribution

  • Snake River and Columbia River systems.
  • They inhabit elevations above 4,500 feet, preferring pool and meadow areas of cool streams where depths exceed three feet.

Key Locations

  • Clearwater, Snake, Salmon, Selway, Big Wood, South Fork Boise, and Henry's Fork rivers.
  • The South Fork Snake, Henry's Fork, Clearwater system, and Snake River near Lewiston are particularly productive.

Specific Spots

  • Deep, slow holes and pools, particularly where riffles enter deeper water.
  • Focus on larger rivers and streams rather than small tributaries.
  • Target water over a meter deep as they prefer deeper sections than most salmonids.

Mountain Whitefish FAQ

Answers from onWater's species guide.

What flies work for Mountain Whitefish in Idaho?

Prince Nymph (sizes 14-22), unweighted Pheasant Tail (size 18), Baetis Emerger (sizes 16-18), Zebra Midge (sizes 16-20), JuJu Baetis (sizes 16-18), Griffith's Gnat (sizes 18-22), Matt's Midge (sizes 16-20), Mother Shucker (size 18), small beadhead Woolly Buggers (sizes 12-16).

When is the best time to fish for Mountain Whitefish in Idaho?

Winter through early spring offers the best fishing. They spawn from October through December making this period unsuitable for targeting them.

How do you catch Mountain Whitefish in Idaho?

Get flies to the bottom using weighted patterns or split shot, and employ double-nymph rigs when regulations allow. For fly fishing, fish patterns deeper than other mayfly patterns. For spin fishing, drift baits near bottom with minimal weight.

What do Mountain Whitefish eat?

Bottom-feeding opportunists that primarily consume aquatic insect larvae including chironomid midges, mayfly nymphs (Ephemeroptera), caddisfly larvae (Trichoptera), and stonefly nymphs (Plecoptera).

Where do Mountain Whitefish live in Idaho?

Snake River and Columbia River systems. They inhabit elevations above 4,500 feet, preferring pool and meadow areas of cool streams where depths exceed three feet.

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