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Legendary Species · Montana

Arctic grayling in Montana

Thymallus arcticus[1]

6 Montana waters whose agency species list names arctic grayling. Each links to its water page (gauge, regulations, access map, guides and shops) and to the agency list it comes from.

  • 6waters list it
  • 3destination hubs
Painting of an Arctic grayling leaping from dark water toward a fly, its tall dorsal fin raised
Arctic grayling (Thymallus arcticus), painting by Robert W. Hines for the U.S. Fish and Wildlife Service. Artwork: Robert W. Hines, U.S. Fish and Wildlife Service, public domain, via Wikimedia Commons

Montana waters

Most fished first. A species missing from an agency list does not mean it is absent; this page lists only waters whose list names it (at least 5 are needed for a page).

All Montana watersArctic grayling: every state

Identification

  • The most striking features are the large, sail-like dorsal (back) fin and colourful body markings.[1]
    What the source says
    “Its most striking physical features are the large, sail-like dorsal (back) fin and colorful body markings.”
  • The dorsal fin is usually fringed in red and dotted with large iridescent red, aqua or purple spots and markings.[1]
    What the source says
    “Their dorsal fins are typically fringed in red and dotted with large iridescent red, aqua, or purple spots and markings.”
  • USFWS says it is the only grayling species found in North America.[2]
    What the source says
    “They are the only salmonoid with a distinguishing sail-like dorsal and the only grayling species found in North America.”

More on identifying arctic grayling

Status, protections and rules

As each agency stated them on the date read; a rule applies only where its agency says so. Check the current regulations for the water before you fish.

  • In 2020 USFWS announced that Endangered Species Act protections for the Upper Missouri River distinct population segment of Arctic grayling are not warranted.[3]
    What the source says
    “protections for the Upper Missouri River distinct population segment (DPS) of the Arctic grayling are not warranted”
  • The Montana Field Guide says the river-dwelling (fluvial) grayling population in the upper Big Hole River is the last remnant of Montana's fluvial grayling.[4]
    What the source says
    “Consequently, the fluvial or river-dwelling population in the upper Big Hole River are the last remnants”
  • The Montana Field Guide gives Arctic grayling a state rank of S1.[4]
    What the source says
    “State Rank: S1”
  • Historically, grayling also lived in Michigan, but USFWS says the Michigan population has been extirpated.[3]
    What the source says
    “While the Michigan population has been extirpated”

Water temperature in Montana

  • Under Montana FWP's 68°F lineMontana FWP cites a study in which trout “caught and released from water with a temperature above 68 degrees F were far more likely to perish than those taken from cooler water.” Water warms through the day: “Fish in the cool morning hours.”
  • Warm for released troutAbove 68°F, released trout were “far more likely to perish than those taken from cooler water” (the study Montana FWP cites). FWP: “Fish in the cool morning hours — low water flow and rising temperatures combine to stress fish.”
  • 66°F: Montana's cutthroat triggerMontana rule, cutthroat trout waters only: “In cutthroat trout waters, angling restrictions occur when the temperatures reach at least 66 degrees for three consecutive days.”
  • 73°F: Montana's hoot-owl triggerMontana rule: FWP's drought policy provides for angling restrictions “when maximum daily water temperatures reach at least 73 degrees for three consecutive days”; hoot-owl restrictions “prohibit fishing from 2 p.m. to midnight each day.” FWP sets them reach by reach: check the current list.
  • 77°FMontana FWP: “Water temperatures of 77 degrees or more can be lethal to trout.”

Sources: “Giving a hoot”, Montana Outdoors (July–August 2024) (Montana Fish, Wildlife & Parks); Drought and fishing (Montana Fish, Wildlife & Parks); Additional fishing restrictions begin July 22 on several Montana rivers (21 July 2026) (Montana Fish, Wildlife & Parks); Current waterbody restrictions (Montana Fish, Wildlife & Parks).

Destination hubs

Hubs that list one of these waters, or that a water page is near: each has guides, shops, licences and trip planning for the area.

Hatch & season charts

Sources

Every fact on this page is our paraphrase of the page cited beside it, read on the date shown. Rules and seasons change: check the agency's current regulations before you fish.

  1. Arctic Grayling Species Profile, Alaska Department of Fish and Game Alaska Department of Fish and Game, read Oct 24, 2026.
  2. Arctic Grayling (Thymallus arcticus) | U.S. Fish & Wildlife Service U.S. Fish and Wildlife Service, read Oct 24, 2026.
  3. Listing of the Arctic Grayling Not Warranted (press release, Jul 22, 2020; archived) U.S. Fish and Wildlife Service, read Oct 24, 2026.
  4. Arctic Grayling - MONTANA FIELD GUIDE Montana Natural Heritage Program / Montana Fish, Wildlife & Parks, read Oct 24, 2026.