The Swordtail (Xiphoporus helleri) is a popular freshwater aquarium fish species. It is a member of the Poecilidae family and is therefore live-bearing. It is closely related to the platy and can interbreed with it.

The species is named after the elongated lower lobe of the caudal fin (tailfin). This is only found in the male.

Swordtails are easy to keep and well suited to a community aquarium.

The species originally comes from South America.