Twin-barred Platy
is a genus of euryhaline brackish water fish in family Poeciliidae of order Cyprinodontiformes. The type species is P. vivipara. Live-bearers, the Poecilia species are collectively known as mollies, with the exception of Endler's livebearer (P. wingei) and the famous guppy (P. reticulata). Members of this genus are members of the family Poecilidae, which includes the southern platyfish or "platy" (Xiphophorus maculatus), and the green swordtail (X. hellerii).