Brown trout in Montana

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).

• Madison RiverAgency list: Montana Fish, Wildlife & Parks
• Yellowstone RiverAgency list: Montana Fish, Wildlife & Parks
• Blackfoot RiverAgency list: Montana Fish, Wildlife & Parks
• Clark Fork RiverAgency list: Montana Fish, Wildlife & Parks
• Bitterroot RiverAgency list: Montana Fish, Wildlife & Parks
• Rock CreekAgency list: Montana Fish, Wildlife & Parks
• Beaverhead RiverAgency list: Montana Fish, Wildlife & Parks
• Jefferson RiverAgency list: Montana Fish, Wildlife & Parks
• Big Hole RiverAgency list: Montana Fish, Wildlife & Parks
• Smith RiverAgency list: Montana Fish, Wildlife & Parks
• Ruby RiverAgency list: Montana Fish, Wildlife & Parks
• Gallatin RiverAgency list: Montana Fish, Wildlife & Parks
• Boulder RiverAgency list: Montana Fish, Wildlife & Parks
• Bighorn LakeAgency list: National Park Service (Bighorn Canyon National Recreation Area)
• Ennis LakeAgency list: Montana Fish, Wildlife & Parks
• DePuy Spring CreekAgency list: Montana Fish, Wildlife & Parks

Identification

• In California, the brown trout is the only trout with both red and black spots on its body. The dark spots on its sides usually have a pale halo.[2]
  What the source says

  “Only trout in California with both red and black spots on body. Dark spots on the sides typically surrounded by a pale halo. Coloration is usually dark to olive brown on the back, shading to yellow on the sides, and yellow or white on the belly.”

• Michigan DNR points to a broad, square tongue with 11 to 12 large teeth, light pectoral fins and a square tail. Lake-run browns are mostly silver, and their spots can be hard to see.[1]
  What the source says

  “Dorsal and adipose fin, broad square tongue with 11 to 12 large teeth, light pectoral fins, square tail, and nine to 10 rays in the anal fin. Lake-run browns are predominately silver in color and the body spots are often obscured in lake-dwellers compared to the resident stream dwellers.”

More on identifying brown trout

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.

• The U.S. Geological Survey reports that brown trout have been linked to declines in native fish, including other trout and salmon, through predation, displacement and competition for food.[3]
  What the source says

  “Brown Trout have been implicated in reducing native fish populations (including other salmonids) through predation, displacement, and food competition (Taylor et al. 1984).”

• Yellowstone National Park rule: in the Firehole River, Madison River and lower Gibbon River (below Gibbon Falls), all rainbow and brown trout must be released.[4]
  What the source says

  “Firehole River, Madison River, lower Gibbon River (downstream of Gibbon Falls)—possession of up to five brook trout is allowed. Catch and release all rainbow and brown trout.”

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.

• Bozeman & Livingston, Montana6 brown trout waters
• Ennis & the Madison Valley, Montana6 brown trout waters
• Missoula, Montana4 brown trout waters
• Island Park & the Henry's Fork, Idaho1 brown trout water

Hatch & season charts

• Northern Rockies8 sourced rows

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. Brown trout Michigan Department of Natural Resources, read Oct 24, 2026.
2. Fishing for Brown Trout (non-native) California Department of Fish and Wildlife, read Oct 24, 2026.
3. Brown Trout (Salmo trutta) - Species Profile U.S. Geological Survey, Nonindigenous Aquatic Species program, read Oct 24, 2026.
4. Fishing - Yellowstone National Park (U.S. National Park Service) National Park Service, read Oct 24, 2026.