Montana Field Guide

Pearl Dace - Margariscus margarita

The pearl dace is a native of both the eastern and northern drainages within the Glaciated Plains ecoregion of Montana, and is an indicator species of the Coolwater Northern Redbelly Dace Assemblage. Pearl dace are not abundant at the relatively few sites in cool, small streams and ponds they are known to inhabit, so they are designated a Montana Fish of Special Concern. Unlike most of the minnows, males establish and defend territories during the spawning season. Their diet includes a wide variety of plants and animals. Pearl dace grow to a maximum length of about 6 inches.

The pearl dace has a dark back, sides that are dusky-silver, and a white underside. Scattered dark lines give some individuals a speckled appearance. Young have a dusky midline band that fades on large specimens but may be distinct on the caudal peduncle. Breeding males are orange-red on the sides and below. A small, flaplike barbel is present in the groove of the upper lip just above each corner of the mouth, and is sometimes absent from one or both sides. A lateral line usually complete.

Montana Range

Pearl dace prefer small cool streams, either clear or turbid (Brown 1971). They spawn in clear water at depths of 1 to 2 feet over a gravel or sand bottom (Brown 1971).

Pearl dace eat a variety of aquatic organisms including insects, crustaceans, worms, and small fish (Brown 1971).

The species is sexually mature in two years and spawns during spring near the bottom (Brown 1971).