Poeciliopsis lucida, the clearfin livebearer, is a species of small freshwater fish in the family Poeciliidae.

It is one of several species of small livebearing fish endemic to Mexico that were described in 1960 by the American ichthyologist Robert Rush Miller.

In the laboratory, brother-sister matings have been going on for many years without any sign of diminution of fecundity from inbreeding.

The triploid individual reproduces by gynogenesis, a process triggered by the presence of sperm but not involving gametic fusion.

[3] P. monacha are highly cannibalistic and the juvenile fishes tend to hide from their mother close to the substrate.