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Montana Field Guide

Montana Field Guides

California Golden Trout - Oncorhynchus mykiss aguabonita

Non-native Species

Global Rank: G5T1
State Rank: SNA

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General Description
The golden trout is a California species that was introduced in Montana in 1907. There are currently about 20 golden trout populations in the high mountain lakes of western and southcentral Montana. They provide a unique opportunity to catch a beautiful fish in a pristine environment. Golden trout up to 4 pounds have been caught in Montana but typical size is usually 6-12 inches. Golden trout are spring spawners and can usually be found in inlet or outlet streams to high mountain lakes around the Fourth of July. Like other mountain lake trout species, they are opportunistic feeders, surviving off a variety of aquatic and terrestrial invertebrates.

Species Range
Montana Range Range Descriptions


Observations in Montana Natural Heritage Program Database
Number of Observations: 89

(Click on the following maps and charts to see full sized version) Map Help and Descriptions
Relative Density



(Observations spanning multiple months or years are excluded from time charts)

Migrates from lakes into tributary streams to spawn.

Found only in mountain lakes in Montana; also successful in clear, cool lakes at lower elevations . Spawns in redds over clean gravel of fist size and smaller. Spawns mostly in outlets, but also in inlets and occasionally along lake shoals.

Food Habits
Aquatic insects are most important, but other aquatic insects and terrestrial insects are important ant times. May feed at benthos, in water column, or at surface. Zooplankton rarely taken.

Readily hybridizes with cutthroat and rainbow. Demise of former 50+ populations of golden trout largely due to introduction of other spring spawning species, whether by hybridization or replacement.

Reproductive Characteristics
Spawns June-July at ice-out at water temperatures of 44-58 degrees F. Sexually mature: usually 3-4 years; sometimes 2 years. Incubation: about 46-52 days at temperatures of 46-52 degrees F. Fry emerge in early September.

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Citation for data on this website:
California Golden Trout — Oncorhynchus mykiss aguabonita.  Montana Field Guide.  .  Retrieved on , from