Blackstripe Topminnow

Characteristics

A slender-bodied, almost cylindrical topminnow; the top of its head and nape are flattened. The snout is pointed, and the mouth is small, oblique and opens dorsally. It has a projecting lower jaw with very small teeth in bands on both jaws. The dorsal fin is far posterior on the back and is inserted into the body behind the origin of the anal fin and has 8 to 10 rays. The anal fin has 12 rays, pelvic fin 6 rays, and the caudal fin is rounded. The lateral line is incomplete with 31 to 36 large, cycloid scales in a lateral series. Its back and upper sides are olive and white below. The sides have a dark stripe, nearly straight edged in females and with crossbars in males. Adults average 1.5- to 2.5-inches long with a maximum of just over 3 inches. Males grow larger than females.

Distribution

Streams in eastern Iowa; has been collected in Pools 16 through 20 in the Mississippi River.

Foods

Aquatic and terrestrial insects.

State Record

State Records are not documented for non-game species.

Expert Tip

None

Details

The Blackstripe Topminnow is found mostly in eastern Iowa throughout the Cedar River drainage, parts of the lower Iowa River drainage and in the Mississippi River. Pre-1900, it was reported in the North Raccoon and South Skunk Rivers as well. It is the most abundant and widely distributed topminnow over much of its range, and has increased in distribution since the 1940’s.

The Blackstripe Topminnow lives in many habitats, from small streams and ditches to large lowland rivers, sloughs, swamps, and oxbow lakes. It can be found in clear water, but commonly lives in low gradient streams of moderate to high turbidity. It prefers quiet margins and pools without strong current. It often is found in areas with some aquatic vegetation, over a variety of bottom types. 

Blackstripe Topminnows usually travel in pairs of a male and a female during the late spring and summer spawning season. The pair defends the spawning territory against others of their own species. Eggs are dropped singly on aquatic vegetation as the pair lie side by side. Up to 20 to 30 eggs can be deposited over a short time, which is usually repeated after several days. 

The Blackstripe Topminnow is viewed as vulnerable according to the Iowa Wildlife Action Plan.

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.

Iowa Department of Natural Resources, Iowa Wildlife Action Plan

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

Illustration by Maynard Reece, from Iowa Fish and Fishing.