Crystal Darter (Crystallaria asprella)

Status: State Endangered (1979).

Occurrence: Not abundant anywhere in its range which includes: the Mississippi River, lower Wisconsin, lower Black, lower Trempealeau, lower Red Cedar Rivers, and Chippewa River in Pepin and Dunn Counties (where it is most common). A map outlining Pre-1977 and 1997 to Present Distribution is available.

Aid to ID: Extremely slender body with distinctly forked tail, pronounced snout and translucent body. Back and upper sides yellowish green, three or four broad saddle marks over back, 10 to 12 dark, oblong blotches along sides. Adult length: 5-6 inches (127-152mm).

Habitat: Larger, deeper rivers in clear to slightly turbid (cloudy) waters and moderate to strong currents. Prefer extensive sandy riffles, bars and pool bottoms that are clean and at least 2 feet (60cm) under water.

Food Habits: Eat mayflies, midgeflies, caddisflies, water scavenger beetles and nematodes.

Natural History: Primarily nocturnal, they prefer deeper waters during the day (6-16' or 2-5m) and move to the shallows at night or during overcast days. They bury themselves in sand with only the eyes protruding, and dart out at passing prey along the benthic (bottom) surface. Breeding behavior is unknown.

Management Considerations: This species is not easily detected using standard fish survey methods. The use of special bottom gear along with night collecting improves the chances of detection and making status determinations. Dams are responsible in part for reducing suitable habitat and can cause population isolation.

Information compiled from publication ER-091.