The Lahontan redside (Richardsonius egregius) is a cyprinid fish of the Great Basin in eastern California and western Nevada.

Lahontan redsides are noted for their breeding colors, consisting of a bright red stripe with a yellow border on each side.

At other times, the stripe is still visible, but the red is much reduced, leaving a gradual transition from the olive-colored back to silvery underside.

The actual egglaying and fertilizing consists of subgroups swimming down and pressing themselves on the bottom, the eggs then adhering to the rocks and crevices.

A variety of common names make reference to the breeding colors, including redside minnow, red-striped shiner, Lahontan redshiner, etc.