Fish Iowa - Fish Species - Johnny darter

Characteristics

A small member of the darters, reaching a maximum of about 2 1/2-inches long. It is olive in color with numerous, conspicuous w-shaped markings along the sides. The dorsal fin has 12 rays, the anal has 8 rays; there are usually about 50 scales along the lateral line, and the breast and cheeks are scaleless.

Foods

Chironomids, tiny crustaceans, small insect larvae

Expert Tip

Darters play an important role in aquatic food chains and are some of the most colorful fish in Iowa.

Details

Habitat preference is diverse. They are found in streams of various size, gradient, substrate and clarity. Of all the darter species, it may be the most tolerant of diverse conditions. It is not a riffle species, and is often found in small to medium-sized streams of moderate clarity, where it lives in pools over sand or solid bedrock.

Spawning activities of this fish have been examined intensively. The males establish territories around partially embedded rocks in the spring when the water temperature is 60 degrees. A nest site is prepared by turning upside down and rubbing the area with the caudal, anal and pelvic fins, while balancing with the aid of the pectorals. Gravid females are approached with fins lowered and are led beneath the rock where nest polishing is resumed. The female may then join the male, head to head, and deposit 30 to 200 eggs in the nest. Females may lay 5 or 6 egg clutches, and males sometimes collect a thousand or more eggs from several females. Males then guard the eggs until hatched.

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

 

State Record(s)

Master Angler Catches