A small snail-eating darter (Percina tanasi) that formerly was found only in the Little Tennessee River. It was thought to have become extinct after construction of a dam, but later was discovered in several other Tennessee streams. Rare species (Percina tanasi) of darter that originally was found only in the Little Tennessee River in the southeastern U.S. It became the subject of a legal controversy in 1978, when its status as an endangered species delayed for two years the construction of Tellico Dam. The situation was resolved when the fish was successfully introduced into the Hiwassee River