Xiphophorus montezumae

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.

The most suitable conditions for Montezuma swordtails include a water temperature of around 21–25 °C (70–77 °F). Water pH should stay near 7.5 at all times. They are quite resilient fish. They come from the Pánuco River basin in northeastern Mexico in the states of Tamaulipas, San Luis Potosi and Veracruz. They are often found in fast-flowing rivers. In the wild, schools with more females than males are common, and they enjoy dense aquatic foliage to give birth in. They reproduce quickly and often, and the fish prefer live foods and aquatic plants over tropical fish foods and fake plants. On average, females will give birth to about 50 fry once every seven weeks. Like almost all swordtails, the Montezuma swordtail will readily breed with platies.

Alderton, David (2005). Doran, Joanne; Tuite, Simon; Griffiths, Lee; Heilman, Christine (eds.). Encyclopedia of Aquarium & Pond Fish. Photography by Max Gibbs. Dorling Kindersley. ISBN 0756668387.