Etheostoma gracile, the slough darter, is a small fish species of least conservation concern in the darter (Percidae) family. It inhabits slow to moderately flowing waters and with substrates that are predominantly mud, silt, or sand. Major food sources include chironomids, copepods, and cladocerans, as well as mayflies in the spring. Adults reach 35 to 50 mm (1.4 to 2.0 in) total length. It is one of the 324 species of fish found in Tennessee.