The Sonora chub is a small (5-7 inches), stream-dwelling minnow found only in the Rio de la Concepcion drainage in the U.S. and Mexico. The body is relatively chubby and dark-colored, with two prominent, black, lateral bands above the lateral line and a dark, oval basicaudal spot. Breeding individuals are brightly colored, with red and orange on fins and belly. Males appear to be brighter colored than females.