The redfin darter is a moderately stout darter with about 12 indistinct dark crossbars on the back. An enlarged black scale is present above the base of the pectoral fin; the cheek beneath the eye has a dusky vertical bar; another bar extends forward from the eye onto the snout. The gill covers are broadly connected by a membrane across the throat. The belly is scaled, but the scales are often small and inconspicuous. The lateral line usually ends beneath the soft dorsal. The back is mottled olive brown; crossbars (if present) are dark brown. The sides are light brown with scattered pale spots. The belly is white with scattered dusky specks. The dorsal, tail, and anal fins have faint brown bands.
Breeding males have scattered red spots on the body; the spinous and soft dorsal fins are dusky with reddish spots at the base, followed by an orange-red stripe and a blue outer margin; the tail fin is similar in color to the dorsal fins, with 2 orange-red spots at the base; the anal fin is mostly red with a blue margin; the pelvic fins are dusky blue.
Adult length: about 1¾ to 2½ inches; maximum about 3 inches.
Currently only occurs in the lower Spring River and its North Fork, in Jasper and Barton counties (in southwestern Missouri). Formerly known from localities in Newton and Douglas counties.
Habitat and Conservation
In our state, the redfin darter occurs on gravel and shale riffles of small- to medium-sized prairie and Ozark border rivers. It is part of a highly distinctive fish community living in the lower Spring River and its North Fork, in Jasper and Barton counties. As the landscape transitions from prairie to Ozarks, the stream character changes, there, too. Human activities have degraded the waterways in this unique transition zone between prairie lands and Ozark hills, endangering the fish.
Little is known of the redfin darter’s habits, but apparently they eat aquatic insects like many other darters.
State endangered; a Species of Conservation Concern in Missouri. Although populations also exist in nearby Kansas and Arkansas, the redfin darter is vulnerable to extirpation within our borders. To keep it from vanishing, we must protect its current and potential habitat by not damming its streams, by protecting against sedimentation, and by preventing pollution and agricultural runoff from degrading the streams.
Little is known of the redfin darter’s breeding habits. In Kansas, this species reproduces in April.
Darters have been called the “hummingbirds of the fish world” because of the brilliant and varied colors of the breeding males. The next time you admire the colorful fish at a pet store, remember that our own native species possess the same kind of beauty — and that some of them are endangered.
As part of a distinctive community of fishes, the redfin darter represents a rare and important component of Missouri’s natural wealth. Other fish of this unique transition zone from prairie lands to Ozark hills include the western slim minnow, Neosho madtom, and channel darter.