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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.


Brook trout (Salvelinus fontinalis)


Brook trout were introduced to Idaho in the late 1800's in an attempt to duplicate their popularity in the eastern United States. Like bull trout, brook trout are char and spawn in the fall. The genetic similarities and habitat overlaps of the two species have resulted in unfortunate hybridization between the two species in many areas, further threatening bull trout populations. Brook trout are also a threat to native cutthroat and rainbow trout because of their highly aggressive nature and slightly larger size as fry. Brook trout are moderately popular sport fish in Idaho, although their tendency to mature at small sizes in unproductive waters leads to overpopulation and stunting.

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