Original description as Xiphophorus pygmaeus nigrensis:
- Rosen, Donn E. 1960. "Middle-American poeciliid fishes of the genus Xiphophorus". Bulletin of the Florida State Museum, Biological Sciences. v. 5(n. 4), pp. 57-242 (ffm00047)
Conservation: Xiphophorus nigrensis is not evaluated by the international union for the conservation of nature in the iucn red list of threatened species.