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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)

Brown trout (Salmo trutta)

Non-native

Brown trout are native to Europe and western Asia. They were introduced to North America as a sportfish in the mid 1800's. Brown trout are aggressive piscivores (fish eaters) that can grow to large sizes--the record in Idaho is 26 pounds, 6 ounces. Brown trout spawn in mid to late fall in rivers and streams, and spend their adult years in habitats ranging from small streams to large lakes. Anadromous (ocean-migrating) populations have developed in many parts of the world. Brown trout are more tolerant of warm water temperatures than Idaho's native trout species.

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