Find your next day on the water.For businesses: claim your free listing
Legendary Fly GearFish Like a Legend
Search

Legendary Species · Idaho

Rainbow trout in Idaho

Oncorhynchus mykiss[1]

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

  • 230waters list it
  • 3destination hubs
Illustration of a rainbow trout in side view: olive back with small black spots and a pink band along the side
Rainbow trout (Oncorhynchus mykiss), illustration by Duane Raver for the U.S. Fish and Wildlife Service. Artwork: Duane Raver, 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 watersRainbow trout: every state

Identification

  • Rainbow trout vary a lot in colour and shape. Adults are silver with many small black spots, a pink or red band along the side, and spots that often run in lines along the tail rays.[2]
    What the source says
    “Highly variable in color and body shape, especially between resident fish and steelhead. Adults are silver and heavily spotted with small black spots. Iridescent pink or red along the lateral band. Numerous black spots pepper the body and dorsal fin, often radiating in lines along the rays of the tail.”
  • The cheeks are pink and the back ranges from iridescent blue to nearly brown, with silver, white or yellow sides and belly. Young fish carry large, dark oval parr marks along the lateral line.[2]
    What the source says
    “Opercula (cheeks) are pink, the back iridescent blue to nearly brown, and the sides and belly silver, white or yellow. Juveniles have oval parr marks along the lateral line that are large and dark.”
  • Rainbow trout and steelhead are the same species. Rainbows stay inland, while steelhead are the form that migrates to the ocean or, in Michigan, the Great Lakes.[1]
    What the source says
    “Genetically rainbow trout and steelhead are the same species but lead very different lives. Rainbow trout stays inland, and an anadromous form that migrates to the Great Lakes (or ocean in their native habitat).”

More on identifying rainbow 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.

  • In Great Smoky Mountains National Park, rainbow trout are non-native. The National Park Service says rainbow trout introduced in the early 1900s, together with logging, cost native brook trout 75% of their habitat.[3]
    What the source says
    “In the early 1900s, significant environmental changes occurred in the park due to logging and the introduction of non-native rainbow trout, which destroyed 75% of the native brook trout's habitat. Rainbow trout out-competed brook trout by reproducing at a faster rate as well as growing faster, taking over the streams.”
  • Yellowstone National Park rule: in the Lamar River drainage, including parts of Slough and Soda Butte creeks, every rainbow trout caught must be killed. Releasing one alive is illegal there.[4]
    What the source says
    “All rainbow trout, brook trout, and identifiable cutthroat/rainbow hybrids caught in the Lamar River drainage, including portions of Slough and Soda Butte creeks, must be killed—it is illegal to release them alive.”

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. Rainbow trout Michigan Department of Natural Resources, read Oct 24, 2026.
  2. Fishing for Coastal Rainbow Trout / Steelhead California Department of Fish and Wildlife, read Oct 24, 2026.
  3. Fish - Great Smoky Mountains National Park (U.S. National Park Service) National Park Service, read Oct 24, 2026.
  4. Fishing - Yellowstone National Park (U.S. National Park Service) National Park Service, read Oct 24, 2026.