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Fishes of Idaho

How are your identification skills? Do you know which are native and which were introduced? To see photos and descriptions, and learn more about Idaho fish, check out our Fishes of Idaho online database.

There are around 20,000 species of fish in the world. About 58% of these are marine (saltwater) fish, 41% are freshwater fish, and 1% are both. We have around 100 species in Idaho, and the list keeps growing as more non-native fish are released into Idaho waters. There are only 39 species of fish native to Idaho. The rest were introduced--some by accident, but most on purpose.

Sculpins (Cottids)

Mottled sculpin (Cottus bairdii)


The mottled sculpin has a discontinuous distribution throughout much of North America. In the west, it is found in the upper Columbia, Missouri and Colorado drainages. It also is found in the Bonneville and Harney basins. In Idaho, it is found in the Snake River and tributaries above Shoshone Falls, the Bear River basin, and the Clearwater and Salmon Rivers and some of their tributaries. They prefer cool, clear streams with moderate to rapid current and are associated with rubble, gravel, or rocky bottoms. They seldom are found in silted areas. This species spawns in the spring. Females deposit adhesive eggs in a crevice or under rocks in clusters of 20 to 150. The male guides her to the nest area and guards the nest after she leaves the area. The female produces from about 50 to 300 eggs, depending on her size. They feed on a variety of aquatic invertebrates, mostly insects, but also may include shrimp, snails, fish eggs and fish fry. The species is large by freshwater sculpin standards, reaching a length of 5 inches. They were thought to be serious predators on trout eggs and fry, but results of studies on their food habits have revealed that few trout eggs or fry are actually eaten. Mottled sculpins are much more important as forage for trout.

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