Bigmouth Shiner

Characteristics

A unique body form; slender, fairly 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 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 have 8 rays, while the pectoral fins have 14 or 15 rays.

Distribution

The Bigmouth Shiner is one of the most abundant and widespread fish species in Iowa. It is found in nearly all rivers and streams throughout the state, occasional in man-made lakes and reservoirs, and rare in natural lakes. With Iowa in the center of its continental range, the distribution of the Bigmouth Shiner is expanding due to changes in prairie stream habitats.

Foods

Aquatic insects, detritus and plant material.

State Record

State Records are not documented for non-game species.

Expert Tip

One of the most important forage fishes in streams and an important bait minnow.

Details

Bigmouth Shiners are common in small, low to moderate-gradient prairie streams with slight current and unstable sandy bottoms. They are most abundant in streams with permanent flow. They can adapt to changing water levels, turbidity and pollutants, but need a sand substrate not covered with silt. In Iowa, they are one of the few species able to live in the sterile sand flats common in Iowa creeks. Some researchers have found that Bigmouth Shiners live in cool creeks, but in Ohio they were found to be uncommon or absent in cool streams.

Spawning occurs in May through July. Adults reach about 3-inches long. 

Recent stream sampling information is available from Iowa DNR's biological monitoring and assessment program.

Sources:

Harlan, J.R., E.B. Speaker, and J. Mayhew. 1987. Iowa fish and fishing. Iowa Conservation Commission, Des Moines, Iowa. 323pp.

Loan-Wilsey, A. K., C. L. Pierce, K. L. Kane, P. D. Brown and R. L. McNeely. 2005. The Iowa Aquatic Gap Analysis Project Final Report. Iowa Cooperative Fish and Wildlife Research Unit, Iowa State University, Ames.

Photo credit: Photo courtesy of Konrad P. Schmidt, copyright Konrad P. Schmidt.