Latin name

Xiphophorus hellerii

Identification

Green swordtails have elongated, narrow bodies that are flattened on the sides. They also have large eyes and a superior mouth.

Features of fish fins

In males, the lower part of the caudal fin forms an outgrowth that resembles a sword (hence the name). They also have a gonopodium — an anal fin that has been transformed into a sexual organ.

Fish colouring

There is little difference in colouration between the sexes. The colouration of males is a greyish-olive background with a longitudinal red stripe and some more reddish stripes running parallel to it. Females are paler. Hybrid forms can be black, red, lemon and other colours.

Distribution

The genus Xiphophorus is represented by species inhabiting bodies of water in Central America, primarily along the Atlantic coast of Mexico, Guatemala and Honduras.

Habitat

Green swordtails can be found in both mountain rivers with turbulent currents and in the lower reaches of these rivers, as well as in lakes, marshes and lagoons.

Size

In the wild, the body length of males is up to 8 cm and that of females is up to 12 cm.

Behavior

This is a peaceful fish that can be kept alone, in pairs or in groups.

Food and feeding habits

It prefers live food such as tubeworms, moths, bark, daphnia and cyclops, but will also eat flakes and canned food. It can tolerate long intervals between feedings, especially if there are live plants in the aquarium as it can feed on the various types of algae that grow on the leaves of higher plants and the walls of the aquarium.

Reproduction

Live-bearing. When the aquarium is overpopulated with females, the swordfish change sex. The females grow a conical 'sword' tail fin and a sexual organ. Almost 80-90% of offspring from a pair of females or a former female are female.

Aquarium conditions

The water temperature should be between 22 and 26 °C. It tolerates a drop in temperature down to 15 °C well. Water hardness: 8–25 °dH. Water acidity: pH 7–8. Water aeration is desirable. However, the aquarium tolerates aeration well when not overcrowded.