Greenfin Darter

The greenfin darter is primarily restricted to the fast-flowing, mountainous streams and rivers of the upper Tennessee River drainage area, in North Carolina, Georgia, and Tennessee. The species' range stretches from the upper Holston and Watauga Rivers, south through the French Broad and Little Tennessee Rivers, and ultimately ends at the Hiwassee River.

The greenfin darter is a benthic insectivore, feeding mainly on insect larvae in cold, high-elevation creeks and rivers. A study by Bryant et al. revealed the diet of the greenfin darter may be the most diverse in the genus, with some individuals' guts containing up to 15 different species of insects. Its predators are mainly larger freshwater fish, such as smallmouth bass (Micropterus dolomieu) and madtoms (genus Noturus). Darters in general are important food sources for many fish. Freshwater eels commonly consume adult darters, and suckerfish prey on their eggs. The species is relatively abundant, and has been found to hybridize with N. camurus and N. rufilineatus, where ranges overlap. Like many other darter species, the greenfin has adapted morphologically to reduce drag and allow stationary positioning on the substrate even in the midst of fast-flowing riffles.