New York Natural Heritage Program
Iowa Darter
Etheostoma exile (Girard, 1859)
Ray-finned Fishes

Identifying Characteristics [-]
The Iowa darter is a slender fish, with a body that tapers anteriorly and posteriorly. It is mainly olive-brown in color, becoming paler to almost white moving ventrally down the body. The lateral line is pale. There are a series of dark vertical bars on the side of the body and under the eye. The anterior dorsal fin is spinous with a blue tinge at the base and margin in males, and the posterior dorsal fin is composed of rays with dark spots along the rays. The tail is square-shaped with dark spots. The pectoral fins have some flecking and the pelvic and anal fins are translucent with little to no flecking. During breeding season, the males change color. The vertical bars on the body turn bluish-green and the spaces between the bars becomes red in color, gradually turning orange at the belly. The spiny dorsal fin acquires a pattern of alternating blue and red horizontal stripes. Juveniles resemble female adults (Smith 1985; Page and Burr 1991).

Characters Most Useful for Identification [-]
The bright blue and red color pattern on males during breeding season is useful in distinguishing Iowa darters from other darters (Page and Burr 1991).

Best Life Stage for Proper Identification [-]
Adults, especially breeding males exhibit the characters useful in identifying Iowa darters.

Behavior [-]
Iowa darters do not typically school except during breeding season. They become mature at one years old. Males establish territories. Females can mate with several males and deposit eggs on roots, sand or gravel (Copes 1976).

Diet [-]
Iowa darters feed mainly on tiny crustaceans when they are young and feed on amphipods, midge larvae, and other insect larvae and aquatic organisms as they get older (Copes 1976; Smith 1985).
Iowa Darter Images
click to enlarge
The Best Time to See
Iowa darters are present year-round, with spawning occurring in the spring and lasting through summer (Smith 1985).
Active Reproducing
The time of year you would expect to find Iowa Darter active (blue shading) and reproducing (orange shading) in New York.
Similar Species
  • Swamp Darter (Etheostoma fusiforme)
    Swamp and Iowa darters are very similar except that during the breeding season, male swamp darters do not become brightly colored and develop tubercles on their pelvic and anal fins. In New York, Iowa darters are found mainly in the Lake Ontario and St Lawrence watersheds whereas swamp darters are confined to eastern Long Island.