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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.

(Salmonoids)

Steelhead (Oncorhynchus mykiss)

Native

Steelhead are an anadromous (ocean-migrating) form of rainbow trout. After hatching in streams and rivers of Idaho, steelhead typically spend a year in freshwater before migrating to the ocean. Steelhead then spend one to two years in the ocean growing to large sizes before returning to spawn. Those that spend one year in the ocean generally return as 5-8 pound fish, whereas those that spend two years in the ocean are often 12-20 pounds. Although strong returns of hatchery steelhead are still enjoyed by anglers throughout the state, the number of wild steelhead is declining.

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