Cyprinodon rubrofluviatilis, known as the Red River pupfish, is a species of killifish from the United States. It is found only in the Red River of the South and Brazos River drainages of Texas and Oklahoma, It grows to a total length of 58 mm (2.3 in) and feeds on midge larvae and other insects. It was first described by Henry Weed Fowler in 1916, as a subspecies of the species Cyprinodon bovinus; the specific epithet rubrofluviatilis refers to the Red River.