Duskytail Darter (Etheostoma percnurum)

Description: 

The Duskytail Darter is a federally endangered species found only from a small portion of the Clinch River System in southwest Virginia. They live near the banks of creeks primarily in pools with gravel substrate. Like other members of the subgenus Catonotus, this species spawns on the underside of flat rocks. In this group, males of some species have knobs on their first dorsal fin that are hypothesized to serve as an “egg-mimic” to attract females for spawning.