Blackside Darter

Characteristics

A moderate-sized darter reaching a maximum length of about 4-inches. It is greenish-yellow with seven oblong splotches connected along the sides and irregularly mottled on the back. The cheeks are covered with small scales. The dorsal fin rays number 12, and the anal fin has 9 rays.

Distribution

Widespread in the Mississippi River basin. It has also been documented in the Lower Big Sioux and Floyd Rivers in the northwestern corner of the state. Common in small to medium-sized streams, the Blackside Darter is one of Iowa’s most abundant and widespread darters.

Foods

The primary food source is mayfly larvae.

State Record

State Records are not documented for non-game species.

Expert Tip

The Blackside Darter can leap out of the water to capture flying insects.

Details

This darter is found in a variety of habitats, including gravel riffles, chutes with steady flow and pools. It usually avoids large rivers. The blackside is unique among the darters in that it has a partially developed air bladder. It often swims in mid-water and may leap out of the water to capture flying insects. It is better suited to slowly rather than rapidly-flowing water. 

The main habitat of the Blackside Darter is in pools and sluggish riffles, mostly in areas of fast and lessening currents connecting the pools and riffles, of medium-sized creeks and rivers with substrates ranging from sand to detritus, silt, boulders and rubble. It prefers streams of low to moderate gradient. The young live in backwaters among piles of sticks, leaves and other debris. The Blackside Darter is more tolerant of turbid and warmer waters than other darters, but highly intolerant of considerable siltation and organic pollutants such as mine wastes. In Kansas, the Blackside Darter is labeled as a threatened species.

Spawning starts in the spring when water temperature reaches 60 degrees. Males migrate upstream into spawning pools. They favor depths of 1 to 2 feet and bottoms with sand and gravel. Some ritualistic fighting may happen at this time among the males. A female moves from a downstream pool into the spawning area and is then joined by the males. She burrows into the gravel or sand bottom, which stimulates the male to mount her and fertilize the eggs produced. The spawning act is repeated with a number of males until a collection of as many as 1,700 eggs have been laid. The male is brilliantly colored during spawning, showing flashes of green or gold instead of normal dark pigmentation.

The Blackside Darter remains one of our most abundant species, although habitat destruction causes local reductions.

The Blackside Darter 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

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