Rio Grande darter

The Rio Grande darter (Etheostoma grahami) is a small species of ray-finned fish, a darter from the subfamily Etheostomatinae, part of the family Percidae which includes the perches, ruffs and pike-perches. It is endemic to the lower Rio Grande drainage of the United States and Mexico. It inhabits riffles over substrates of gravel or rubble. This species can reach a length of 6 cm, though most only reach about 3 cm. The Rio Grande darter was first formally described as Oligocephalus grahami in 1859 by the French zoologist Charles Frédéric Girard (1822-1895) with the type locality given as the Devils River in Texas. The specific name honors the American soldier and topographer James Duncan Graham (1795-1865), who led the expedition on which the type was collected by John H. Clark.