Montana Field Guide

The western silvery minnow has been recognized as a separate species only since 1971. It is very difficult to field separate from the plains minnow which it is frequently collected with. This native fish is found in perennial streams and rivers in the prairie ecoregions of eastern MT, and is an indicator species of the Medium Warmwater River Fish Assemblage. Western silvery minnows have long intestines, indicating they are adapted for eating plants and detritus as well as other food items. Specimens grow to a size of about 7 inches in length.

Overall very silvery; back dusty or yellowish olive, underside white. The western silvery minnow has 11 to 17 scales across the belly from lateral line to lateral line.

Makes spawning run to lower Marias River.

Seems to prefer large streams and is less common in creeks and impoundments. Bottom of silt or sand. Showed a preference for pools and backwaters in middle Missouri River study.

Feeds mainly on bottom ooze containing a variety of algae, organic materials and some invertebrates.

Sexually mature at 1 yr. Spawning occurs June - July on middle Missouri River with peak occuring late June - early July.