The Oaxaca killifish or known in Mexico as "escamudo oaxaqueño" (Profundulus oaxacae), It is a small fish of no more than 8 cm, endemic of Oaxaca in Mexico. Gender Profundulus Hubbs, considered the most primitive of order Cyprinodontiformes (Webbs, 1998).
Discovery of the species: The renowned American ichthyologist Seth Eugene Meek, in the year 1901 collected Profundulus oaxacae near San Agustin Yatareni, Oaxaca, Mexico, where he was known as "escamudo oaxaqueño" a year later made the description and originally called Fundulus oaxacae, five years after it was considered synonymous with Fundulus punctatus (now P. punctatus), until in 1999 was again recognized as a different genetic level species, but already severely threatened, including declared extinct in the type locality.
Historic distribution: Endemic sub-basin and basin "Río Mixteco" and the sub-basin "río Atoyac-Oaxaca de Juárez" watershed Atoyac or Verde River.
Habitat: small to large streams; clear water very muddy; mild, zero current to fast; background of sand, gravel, pebbles; dense cloaks floating and submerged of green algae on the banks of streams; depth 0.5-1.0 m.
Biology: Meek (1902, 1904) found 100 mature eggs (diameter, 1.25 mm approx.) In a female about 30 mm long captured the 4th of May; spawning around the third week of May. Langton (1982, 1984) described the artificial cultivation of this species in very general terms and confusing species with a sister Profundulus punctatus; I held for 15 consecutive years from one original pair. In captivity spawn from 20 ° to 30 ° C (Langdon 1994). LP known maximum 80 mm.
Loss of populations: For the degradation and destruction of habitats. Dr. Emilio Martinez Ramirez, a researcher CIIDIR IPN Oaxaca Unit for the year 1999 suggested that the species should be included in NOM-059-SEMARNAT 2010 (Mexican Standard that protects species at some risk category) based on the evaluation MER (Method of Risk Assessment for its acronym in Spanish) under the category of "endangered species (a)", 2014, to be identified only three people, including the recently discovered in San Lorenzo Cacaotepec (01 June 2014 ) proposes to enter the category "in danger of extinction".