The Sonoyta pupfish or Quitobaquito pupfish (Cyprinodon eremus) is one of the most distinct species in its genus. This pupfish ( Cyprinodon - Genus ) is restricted to the Rio Sonoyta Basin in Sonora, Mexico and south-central Arizona, named the Quitobaquito Springs. The Quitobaquito pupfish is the last remaining major population of fish at the springs. Originally, it was considered to be one of three subspecies of C. macularius, including the nominal desert pupfish (Cyprinodon macularius macularius), and the undescribed Monkey Spring pupfish (Cyprinodon sp.), but it has since been reclassified as a distinct species.