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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.

Suckers (Catostomids)

Largescale sucker (Catostomus macrocheilus)


The largescale sucker is native to the Pacific Northwest, occurring from British Columbia south to Oregon. It is widespread in the Columbia River system. In Idaho, this species is found in the Snake River drainage below Shoshone Falls, and the Spokane, Pend Oreille, and Kootenai River systems. It occurs in the slower-moving portions of rivers and streams, and in lakes. Largescale suckers spawn in the spring in shallow water over sandy areas of streams or the sandy or small gravel shoals of lakes. Females may produce up to 20,000 adhesive eggs. The young feed upon small zooplankton until they become bottom dwellers. Then they feed on benthic aquatic invertebrates, diatoms, and other plant material. This species reaches a length of 24 inches and 7 pounds in parts of their range, but in Idaho most are less that 16 inches in length. The young probably serve as forage for larger predaceous fishes and fish-eating birds.

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