The peamouth is a slender fish, with a somewhat compressed body and a subterminal mouth, large eyes, a rounded snout and a forked tail.

When breeding the mature males develop a red stripe along the sides[3] on the belly, mouth, gill cover and pectoral fin base.

The spawning runs of the peamouth make an impressive natural spectacle as the brightly colored fish move into areas of warm, shallow, flowing water in large numbers.

[2] Each female is normally attended by at least two males and can lay between 5,000 and 30,000 eggs, the amount being dependent on the age and size of the individual fish.

[5] Hybrids between the peamouth and the Northern pikeminnow (Ptychocheilus oregonensis) and the redside shiner (Richardsonius balteatus) have been recorded in Montana.