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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.

Minnows (Cyprinids)

Chiselmouth (Acrocheilus alutaceus)


The chiselmouth is a western species of the minnow family found in the Columbia and Fraser River (British Columbia) systems, and the Malheur basin of eastern Oregon. In Idaho, it is found in the Snake system below Shoshone Falls. It inhabits moderate to slow-flowing streams of all sizes, but can be found in lakes. The species reaches a length of about 12 inches and is considered a herbivore, a plant-eating fish. With the aid of the characteristic hard, sharp plate on the lower jaw, adults feed on algae, mainly diatoms, by scraping the attached material off rocks and other bottom substrate. Young fish consume surface insects in addition to free-floating diatoms. Spawning occurs in late spring or early summer when water temperatures reach about 60 F. Spawning occurs in streams over gravel or small rubble. Each female produces about 6,000 eggs. This species may serve as a major link in the food chain between the primary production of plants to piscivorous fish.

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