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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.

Catfishes (Ictalurids)

Flathead catfish (Pylodictis olivaris)


Flathead catfish are the largest member of the catfish family found in Idaho and the second largest gamefish in the state. The native range of the flathead catfish includes the large warm water streams and rivers of the Mississippi River, Ohio River, lower Missouri River drainage to western Texas and northeastern Mexico. These fish were likely introduced into the Snake River by mistake in the 1940's. Flathead catfish prefer the slow moving water of large rivers and lakes. It is a solitary predator feeding primarily at night. The fish are a dark olive brown color with mottling on the sides, and, as the name implies, characterized by a large, broad, flat head. Young flatheads feed largely on insects, crustacea, worms and small fish, but adults feed almost entirely on fish. Flathead catfish can grow very large, as the Idaho state record of 58 ? pounds demonstrates. Throughout their native range, flathead catfish can achieve weights of over 100 lbs (45 kg) but most weigh 2 to 15 lbs (1 to 7 kgs). It is a popular game fish because it achieves such large sizes and is a hard fighter.

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