Freshwater · Fall and winter best; October to February in cold rivers
Mountain Whitefish
Prosopium williamsoni
A river whitefish of cold western rivers — in BC the Stave, Chilliwack and Harrison, and in Alberta the Bow River, where small nymphs under an indicator are the classic winter method. It is a river fish only: it is NOT present in the tidal Fraser below Mission, where downstream 'whitefish' reports are actually peamouth.
Seasons · Peak
Identifying features
- Small, narrow mouth on a pointed snout — built for bottom feeding
- Single small dorsal fin and a deeply forked tail
- Silvery-olive back with fine dark speckling on the sides
- Small adipose fin between dorsal fin and tail, like its salmon relatives
- Cylindrical body, less deep than a lake whitefish
Habits
- Feeds almost entirely on bottom insect larvae, nymphs and eggs
- Holds in deep runs and pool tailouts in cold water
- Schools loosely and feeds through the coldest winter months
- Spawns in late fall over gravel in flowing water
- Rarely rises to dry flies; most feeding is subsurface
Distribution
Where to find them
- Stave, Chilliwack and Harrison rivers in the Fraser Valley
- Bow River runs and pools through Calgary and downstream
- Cold Okanagan and BC Interior foothill rivers in winter
Where they live
How to catch them
Indicator nymphing River
Rig: Fly rod or light spinning rod, strike indicator with a small weighted nymph fished dead-drift through deep runs
Bait/lure: Small nymphs, midge patterns
Key tip: Keep the nymph right on bottom — mountain whitefish rarely move up for food.
Bottom fishing with tiny bait hooks River
Rig: Light rod, small split shot and a size 12-14 hook with a maggot or single egg, drifted through pool tailouts
Bait/lure: Maggots, single salmon eggs
Key tip: Use the smallest hooks you own; the mouth is small and bites in winter are very light.
Best baits & lures
Baseline setup
- Rod: Light 6-7 ft spinning or 4-5 wt fly rod
- Line: 4-6 lb mono or light fly line with fine tippet
- Terminal: Small nymphs, tiny hooks, split shot, indicators
Recommended gear for this species
Rod · Best value
9' 5-weight fly rod outfit
≈ US$180-260
Covers chironomid lakes and small rivers with one setup.
Flies · Budget
Chironomid assortment (30 patterns)
≈ US$25-40
Chironomids are 60% of a lake rainbow's diet in spring.
Picks come from our rule library — never paid placements. Prices are guides; affiliate links may earn us a commission.
Typical size
Common 10-16 in; large fish to about 20 in and 4 lb
On the table
Good — mild white flesh, best fresh; bony, so many anglers release them.
Similar species
Lake WhitefishLake whitefish is a deep-bodied lake fish with a more downturned mouth taken mostly through ice or nets; mountain whitefish is a slimmer river fish of cold runs and tailouts
Round WhitefishRound whitefish is a more northern, cylindrical fish with a single flap on each nostril; mountain whitefish has two flaps per nostril and is the common river whitefish of BC and AlbertaRegulations vary by area and can change in-season — always check the official rules for your area before you fish. Regulations guide →
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