Xiphophorus montezumae, the Montezuma swordtail, is a livebearing freshwater fish of the order Cyprinodontiformes, family Poeciliidae, and genus Xiphophorus.

Growing to a maximum length of around 7.5 cm (3.0 in), the females are larger in size than the males.

The genus Xiphophorus is common in freshwater aquariums.

The males of this particular species are known for their metallic green scales and the fact that their "sword" stays horizontal unlike most species where it is angled downward.

Doran, Joanne; Tuite, Simon; Griffiths, Lee; Heilman, Christine (eds.).