The redside shiner, Richardsonius balteatus, is minnow native to southwestern Canada and the western (especially northwestern) United States. In Utah, this common species is native to the Bonneville Basin, and has been introduced to the upper Colorado River drainage. The redside shiner prefers heavily vegetated areas of slow-moving water with sand or mud substrate, and members of the species are often found in large schools within such habitat.
Redside shiners are opportunistic feeders, eating insects, mollusks, zooplankton, small fishes, fish eggs, and even algae. The species spawns during the spring and summer over gravel substrate or submerged vegetation. Adhesive eggs are broadcast into the water, fertilized, and then stick to plants, rocks, detritus, or the substrate. Eggs hatch in about two weeks; no care is given to eggs or young.
Although redside shiners are often consumed by sport fishes, they compete with young trout for food and space, and are therefore not as valuable a forage fish as they might otherwise be.