How to Identify Trout Species

Identify Your Trout Species

While some of the species shown here may not look exactly like the trout in your area, the identification characteristics are common enough that you can use them to identify the trout in your streams.

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Rainbow Trout – dark colored rainbow with the rainbow stripe – photo courtesy of US Fish and Wildlife Service. Rainbows can be identified by their heavy single spots all over their skin along with the bright rainbow stripe down the middle.
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Rainbow Trout with more traditional light colored skin and rainbow stripe – photo courtesy of US Fish and Wildlife Service. As rainbows get bigger, they may get more silvery in color but still are heavily spotted with single spots and the rainbow stripe.

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Brown Trout – caught by Larry Plagman – Tarryall Creek, Colorado 6-17-06 used with permission. Brown trout have a brownish colored skin covered with ringed dark spots intermixed with ringed red spots. As they get bigger the dark spots may become less round especially on the upper back which adds to their ability to blend into a stream bottom or a weed bed.
large brown caught by Tad Howard of coloradotrouthunters.com - one of my favorite pictures. used with tad's permission
Large brown trout caught by Tad Howard of coloradotrouthunters.com from Taylor River. this is one of my favorite pictures. Used with Tad’s permission. Notice the heavy ringed red spots on the bottom of the fish fading into darker spots toward the top.
 colorado river cutthroat - photo courtesy of colorado dow and Joseph Tomerelli
Colorado River Cutthroat – photo courtesy of Colorado DOW and Joseph Tomerelli. Cutthroats are less heavily spotted than rainbows and browns but are more heavily spotted toward the tail. They can be identified by the red slash under the chin and the reddish gill plates.
 Rio Grand Cutthroat - photo courtesy of colorado dow and colorado river cutthroat - photo courtesy of colorado dow and Joseph Tomerelli

Rio Grand Cutthroat – photo courtesy of Colorado DOW and colorado river cutthroat – photo courtesy of colorado dow and Joseph Tomerelli. Note the heavy black spots along the midline fading to smaller heavy spotting toward and onto the tail. Also the same reddish colored gill plates.

 Greenback Cutthroat - colorado state fish. photo courtesy of Colorado DOW and Joseph Tomerelli
Greenback Cutthroat – Colorado state fish. photo courtesy of Colorado DOW and Joseph Tomerelli. This is the most beautiful of the cutthroat species in Colorado in my opinion. They can be identified by the greenish coloration on the back and the ringed spots fading to heavy spotting toward and onto the tail.
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Blue River Cutthroat – a nice 20 inch fish caught by Larry Plagman 4/5/06 – used with permission. Notice the red gill plates and red slash under the chin common to cutthroats and the rainbow stripe down the middle common to rainbows. Cutbows can be some of the most beautiful fish in trout streams. Rainbows and cutts will cross breed easily since they are of the same salmonoid family.
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BrookTtrout – photo from wikimedia.org – public domain photo Color Plate Brook Trout from American Fishes by Goode and Gill (1903)brooktrout
Brook Trout – showing white edged fins and red ringed spots – photo courtesy of US Fish and Wildlife Service. Brook trout are technically a member of the char family. They are most often found in high mountain streams and lakes. They require clean water and will usually be the first species to disappear from a stream if the water becomes polluted. They are prolific breeders and often out populate their food supply resulting in small fish. But they can become quite large when caught in lakes.
 Grayling - note the large sail like dorsal fin. Photo courtesy of Colorado DOW and Joseph Tomerelli
Grayling – note the large sail like dorsal fin. Photo courtesy of Colorado DOW and Joseph Tomerelli. Most often known as Artic Grayling because of their normal range. Colorado has stocked some in high mountain lakes and some streams. Usual size is about 12 inches but they can be fun to catch. Grayling require highly oxygenated water cool water. They like the brook trout are sensitive to water pollution and are among the first to disappear if pollution increases. Such has been the case in the Great Lakes.
 Mountain White Fish - photo courtesy of Colorado DOW and Joseph Tomerelli
Mountain White Fish – photo courtesy of Colorado DOW and Joseph Tomerelli. While looking somewhat like a carp, they are great fighters in the larger sizes. The Roaring Fork River in Colorado has a population of large whitefish with some running up to 18 or more inches. They have a small mouth, larger scales than trout and a small flap of skin near the tail.