"There is no greater fan of fly fishing than the worm." --Patrick F. McManus, Never Sniff a Gift Fish, 1979

Westslope Cutthroat Trout
Oncorhynchus clarkii lewisi
(Salmonidae) 

The Westslope cutthroat trout is one of two subspecies of native cutthroat found in the state. Together, they have been designated Montana's state fish. The average size ranges from 6 to 16 inches, depending on habitat, and rarely exceed 18 inches in length. Westslope cutthroat are common in both headwaters, lake and stream environments. They feed primarily on insect life and zooplankton.

It can be difficult to visually distinguish Westslope from other cutthroat trout subspecies, but the westslope cutthroat trout tends to have more small spots by the tail and none by the pectoral fin. The fish is more of a silvery or greenish color. Cutthroat trout tend to thrive in streams with more pool habitat and cover than uniform, simple habitat.


Brook Trout
Salvelinus fontinalis
(Salmonidae)

The "brookie" or brook trout was introduced to Montana from eastern North America in 1889. Brook trout are common throughout most of the western two-thirds of Montana in all major drainages. Brook trout will eat nearly any living organism, and larger fish can be voracious predators on other fish and even their own young. A Flathead River study found ephemeroptera (Mayflies) and trichoptera (Caddisflies) were dominant insects in their diet.

Brown Trout
Salmo trutta
(Salmonidae)

The brown trout belongs to a different genus than native Montana trout species. They evolved in Europe and western Asia and were introduced to North America in 1883 and to Montana in 1889 in the Madison River. Today brown trout are found throughout most of Montana except the northwest and parts of the east.

Generally they prefer lower-gradient, larger streams than cutthroat and rainbow. The state record is 29 pounds, and large fish are not at all uncommon, although 12 to 20 inches is the usual size range of adults. Browns feed largely on underwater aquatic insects.

Rainbow Trout
Oncorhynchus mykiss
(Salmonidae)

The rainbow trout is Montana's number one game fish. Rainbow trout were introduced from numerous hatchery stocks into virtually every suitable habitat in the state, beginning in 1889. Scientists believe that only the rainbow trout of the upper Kootenai River drainage are native to this state.

The state record for rainbow trout is over 33 pounds, and fish of up to 10 pounds are common in some of our most productive waters. Rainbows are efficient at feeding on plankton, aquatic and terrestrial insects, and occasionally some smaller fishes.

Information courtesy of Montana Fish, Wildlife and Parks

Fly Chart: See what flies to use and when.

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