Crystal Darter

Characteristics

A pale yellow, very slender darter with 4 or 5 dark brown cross-bars that extend obliquely forward from the back onto the sides. The underside of the fish is silvery-white. Body length is about seven times greater than depth. The body is fully scaled, except for the breast and belly. The lateral line is complete with 81 to 98 scales. The anal fin has one flexible spine and 12 to 14 rays, and the tail fin is deeply forked. Fins have no definite markings. Adults commonly grow to 2.2- to 3.8-inches, with a maximum length of 5.5-inches.

Distribution

Rare in Iowa; found in the Turkey River as well as Pools 9, 11 and 13 of the Mississippi River. It is also found in a few larger river systems in Missouri.

Foods

A Wisconsin study found this darter eats exclusively the immature states of aquatic insects, with midges, blackflies and caddisflies predominating.

State Record

State Records are not documented for non-game species.

Expert Tip

An unique behavioral trait, the Crystal Darter will burrow itself into sandy substrates with just its eyes showing.

Details

The Crystal Darter occurs sporadically, with only a few fish found at a time. It lives in open channels of large, clear streams over silt-free sand and gravel bottoms. It is found in deeper streams with strong current and low to moderate gradients. Habitat altering activities like channelization, dredging, and impoundment, or anything that increases the silt load, diminish or extirpate Crystal Darter populations. Remaining in only a few pristine streams, the Crystal Darter is absent from large areas in its former range.

Recent stream sampling has not resulted in the discovery of any individual Crystal Darters. 

Like the other darter species in Iowa, these fish have no importance to anglers. It is viewed as critically imperiled according to the Iowa Wildlife Action Plan, but it is not on Iowa's endangered, threatened, or special concern species list (571 IAC 77.2(2) (2015)).

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.

Missouri Department of Conservation, online Field Guide

Pflieger, W.L. 1997. The fishes of Missouri. Missouri Department of Conservation, Jefferson City, Missouri. 372 pp.

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