[2][3][4] The Sonoyta pupfish has a thick, chubby body with a superior mouth filled with tricuspid teeth.

The posterior part of their caudal peduncle (base if the tail) is yellow or orange, and sometimes, an intense orange-red.

[1] In the United States, it only survives in the Quitobaquito springs, a part of the Gila River basin in the Organ Pipe Cactus National Monument of south-central Arizona.

[1] Sonoyta pupfish are found in springs, lakes, pools, marshes and sluggish streams.

[8] Due to habitat changes, predation and/or competition with nonnative fishes, and possible wind drift of harmful chemicals from Sonora, Mexico, the Sonoyta pupfish population is severely reduced; however, the population at the Quitobaquito Springs remains stable, but sometimes ranges from high to low numbers seasonally.