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Legendary Species · Idaho

Brown trout in Idaho

Salmo trutta[1]

34 Idaho waters whose agency species list names brown trout. Each links to its water page (gauge, regulations, access map, guides and shops) and to the agency list it comes from.

  • 34waters list it
  • 2destination hubs
Illustration of a brown trout in side view: golden-brown body with dark spots and red spots ringed in pale halos
Brown trout (Salmo trutta), U.S. Fish and Wildlife Service illustration. Artwork: U.S. Fish and Wildlife Service, public domain, via Wikimedia Commons

Idaho 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 Idaho watersBrown trout: every state

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 Idaho

  • Under 66°FIn the study Idaho Fish and Game cites, trout landed in water under 66°F survived best: mortality “was 69% higher for trout landed at 73°F water temperatures than for those landed when waters were less than 66°F.” In summer, “early-mornings are typically best while the water is still cool.”
  • WarmingIdaho Fish and Game cites a study in which mortality “was 69% higher for trout landed at 73°F water temperatures than for those landed when waters were less than 66°F.” Fish early: “early-mornings are typically best while the water is still cool.”
  • 73°FIdaho Fish and Game: “On those occasions where trout streams do get above 73°F, anglers may want to pause fishing because catch rates are noticeably lower.” Idaho sets no temperature closure: “Idaho Fish and Game is hesitant to close fishing in wild trout waters based on warm water temperatures.”

Sources: Perspective: Trout fishing during low water and high temperatures (25 July 2024; archived copy) (Idaho Department of Fish and Game); The heat is on, but trout and other coldwater fish have been around the block a time or two (9 Aug 2022; archived copy) (Idaho Department of Fish and Game).

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. 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.