Whitefish · Prosopium williamsoni
Mountain Whitefish
Also called Whitey, Rocky Mountain whitefish.
Short answer
The mountain whitefish is a native salmonid of western rivers, silver-grey with large scales, a small downturned mouth and no spots. It is frequently dismissed by anglers, it is native where introduced trout are not, and it feeds through the winter when trout fishing is otherwise slow.
How to identify a mountain whitefish
- No spots
- Plain silver-grey flanks with large visible scales. Nothing patterned about it.
- Mouth
- Small, downturned and sub-terminal, built for picking nymphs off the bottom.
- Adipose fin
- Present — it is a salmonid, and related to the trout it swims with.
- Body
- Cylindrical and firm, with a forked tail and a short dorsal fin.
What a mountain whitefish is
The mountain whitefish is the most under-appreciated fish in the West. It is a true native of the rivers where rainbows and browns were introduced, it is a salmonid with an adipose fin like any trout, and it is abundant — on many western rivers whitefish outnumber trout substantially. Anglers have historically treated catching one as a disappointment, which says more about fashion than about the fish. They feed hard on nymphs through the cold months when trout are sluggish, they take a dry fly in the evening, and the small downturned mouth means they are a genuine test of a delicate presentation.
- Native to
- Native to the rivers of the Rocky Mountain West and the Pacific Northwest, from Nevada and Utah north into Canada.
- Typical size
- Ten to sixteen inches commonly; a fish over eighteen inches is a good one.
- What they eat
- Aquatic insect larvae and nymphs taken off the bottom, particularly midges, caddis and small mayflies. They will rise to a dry fly in the evening.
Where mountain whitefish live
Throughout the Rocky Mountain West and the interior Northwest: Montana, Idaho, Wyoming, Utah, Nevada, Colorado, Oregon and Washington, and north into Canada.
Fly fishing in Montana Fly fishing in Idaho Fly fishing in Wyoming Fly fishing in Utah Fly fishing in Oregon
Conservation status
Native and generally secure, though some populations have declined with warming and sedimentation. A few states have reduced limits in response.
Protected status and the rules that follow from it are set state by state and change. Before you fish, check the current regulations for the water you are standing in — this page is a starting point, not a legal reference.
How to catch mountain whitefish
Fish small nymphs deep and dead drift, exactly as you would for trout, and expect to catch them in the slower, deeper runs. Winter is when they become genuinely useful — on a cold January day on a Montana or Idaho river, whitefish will feed when the trout will not, and a size 18 midge pupa on the bottom will keep a day alive. Take them off the hook gently; the small mouth tears easily.
- They are native. The trout you came for usually are not.
- Winter is their season. They feed when trout have stopped.
- The small mouth tears easily. Handle them as carefully as a trout.
Flies that work for mountain whitefish
Each of these is a card in the deck, and each has a full page in Our Fly-brary.
Keep reading
- How to release a trout — handling, and why it matters more for some species than others
- How to read water — where each of these fish holds
- Hatches and what trout eat — the food these fish are feeding on
- Fly fishing by state — which species you will meet, state by state
Rainbow Trout Brown Trout Brook Trout Cutthroat Trout Steelhead Bull Trout Lake Trout Golden Trout Arctic Grayling Dolly Varden Tiger Trout