Bigmouth shiner is the most widely distributed and abundant minnow in Iowa. They are common to abundant in nearly all rivers and streams, occasional in the man-made lakes and reservoirs, and rare in the natural lakes. Distribution of this minnow is becoming more widespread with each decade as stream habitats are changed into shallow, monotypic water courses. Iowa is the center of its continental range, which includes most of the midwest.

This shiner has a distinctive body form, being slender, relatively flat-bellied and hump-backed. Their eyes appear to focus upward, when viewed from above, because the pupil is skewered dorsally. Body color is olive-yellow on the back and silvery on the sides and belly. A mid-dorsal stripe, running along the top of the body, is continuous around the base of the dorsal fin. There is no pigment around the vent or at the base of the anal fin. There is no lateral band but the lateral line that has about 35 scales and is complete with paired markings called "mouse tracks" at each pore. Scales in front of the dorsal fin are smaller, crowded, and exceed 16 in number. The sub-inferior mouth, found on the bottom of the head and overhung by the snout, is horizontal and does not have a barbel. Hooked pharyngeal teeth on slender arches are arranged in an array formula of 1, 4-4, 1. Dorsal, anal, and pelvic fins contain 8 rays, while the pectoral fins contain 14 or 15 rays.

Bigmouth shiners are one of a few fish species found over the seemingly sterile sand flats that are common in medium and smaller Iowa creeks. They are bottom feeders, utilizing aquatic insects, bottom ooze and plant material. Spawning occurs in May through July. Adults reach about 3 inches in length. This minnow is one of the most important forage fishes in our streams and is an important bait minnow.

*Mayhew, J. (editor). 1987. Iowa Fish and Fishing. Iowa Department of Natural Resources, Des Moines, Iowa. 323 pp.