The many "Xiphophorus" species are all called either platyfish (or platies) or swordtails. The southern platyfish grows to a maximum overall length of . The variable platyfish is bred commercially for the aquarium hobby. IUCN lists the Monterrey platyfish as "extinct in the wild". The southern platyfish has been released probably due to fish farm or aquarium releases. The Monterrey platyfish ("Xiphophorus couchianus") is a species of freshwater fish in family Poecilidae. The northern platyfish ("Xiphophorus gordoni") is a species of fish in the family Poeciliidae. In 1976, an aquarium variety of platyfish, "Xiphophorus maculatus" was found. The Monterrey platyfish is a dull-colored fish, appearing not unlike a female guppy.