The crystal darter is a pale, very slender darter with 4 or 5 dark crossbars that extend obliquely forward from the back onto the sides. The back and upper sides are pale yellow; the underparts are silvery white. The midside has a series of oblong dusky blotches. Fins lack definite markings.
The upper lip is not separated from the snout by a deep groove; instead, it is joined at the midline by a narrow bridge of skin (the frenum). The body is fully scaled except for the breast and belly. Lateral line complete. Tail fin deeply forked.
Length: about 3½ to 5½ inches (adults); maximum about 6 inches.
Historically found in many rivers in east-central and southeastern Missouri. The only recent records are from the Gasconade River in Gasconade County, and four locations on the Black River in Butler County.
Habitat and Conservation
Inhabits the open channels of large, clear streams having low to moderate gradients and extensive stretches of largely silt-free sand and small gravel substrate. Generally found over such substrates where there is a strong current and water depths of about 3 feet.
A Wisconsin study found this darter eats exclusively the immature states of aquatic insects, with midges, blackflies, and caddisflies predominating.
A Species of Conservation Concern, the crystal darter is Endangered in Missouri. Apparently never abundant in our state, its numbers and range have been declining. It was formerly known from the Meramec, St. Francis, and Little rivers, but apparently it has disappeared from those drainages. Channelization, dredging, and impoundments have increased siltation, destroying the clear water this species needs.
The biology of this distinctive darter is poorly known. In Arkansas, it apparently breeds in late winter or early spring. At our latitude, during the first year of life, it grows to about 3 inches. This fish may bury itself in the sand to hide, and apparently it is most active at night.
Missourians can be proud of our state for many reasons. One bragging point we have over most of the neighboring states is the richness of our fish community, including rare types like this nifty little darter. There are more than 200 kinds of fish in our state. Kansas, for example, only has about 140.
As a species that prefers clean, unpolluted streams, crystal darters act as indicators of a healthy ecosystem. Restoring and protecting streams for the crystal darter also will benefit many other aquatic species.