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Whitefish & graylingSalmonidaeG5 (Secure) · ESA: Not listed · Idaho: SNA

Arctic Grayling

Thymallus Arcticus

A rare coldwater salmonid that cruises clear rivers and lakes, often rising to insects.

Overview

Size range

14–30 in

Size range

Typical adult length in the waters we cover.

Water temperature

Coldwater

Water temperature

Preferred thermal regime for this species.

Origin

Introduced

Origin

Stocking and native history where this species is found.

About Arctic Grayling

Arctic grayling are members of the salmon family and are not native to Idaho; NatureServe lists them as introduced in the state. They are a coldwater fish best known for using clear lakes and medium to large rivers, with fish commonly around 14 inches and capable of reaching about 30 inches.

Arctic Grayling Silhouette

Primary

Behavior

spawning: Moves into rocky creeks to spawn.
feeding style: Often feeds in open water and near the surface, especially on drifting or adult insects; fish can also take small fish, fish eggs, and crustaceans.
seasonal notes: Young fish start on zooplankton and shift toward immature insects as they grow. Adults commonly school in moderate numbers and are most associated with cold, clear water.

Habitat

water types: clear lakes, medium rivers, large rivers, rocky creeks
preferred holds: Look for fish in clear, cold open water, especially lake margins, river runs, and areas near inlet or outlet sections connected to spawning tributaries.

Where Found

Blue Ribbon waters

Salmon River
Salmon River

Recommended waters

Kootenai River
Kootenai River

Diet

Young grayling feed on zooplankton and immature insects; adults mostly eat surface insects but will also take eggs, small fish, and crustaceans.

Also likely eats (inferred from shared waters):

Angler Tactics

tactics: Match insect activity first. Cover open-water edges, gentle runs, and inlet-outlet zones with light tackle, and watch for schooling fish that may cruise or rise in clear conditions.
effective methods: dry flies, nymphs, small spinners, small spoons

Regulations

Idaho-specific Arctic grayling fishing guidance was not clearly linked on IDFG pages consulted. Always check the current Idaho fishing seasons and rules for the water you plan to fish.

Regulations vary by water. Check current Idaho Fish and Game rules before fishing.

Conservation

Status: Introduced to Idaho

G5 (Secure) · ESA: Not listed · Idaho: SNA

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