Green swordtail

Xiphophorus hellerii

FreshwaterFish

Care at a glance

Temperature: 68–82°F (20–28°C)
pH: 7.0–8.0
Adult size: 5.9 in (15 cm)
Minimum tank: 24 gal (90 L)
Temperament: Peaceful
Social behavior: Social
Swim level: Middle
Difficulty: Beginner
Breeding: Easy
Rarity: Very common
Origin: Mexico, Central-America
Family: Poeciliidae

Overview

Swordtails are peaceful and social, so keep a small group, ideally with more females than males to spread out male attention. They are active mid-water swimmers and appreciate length to cruise. Keep them in hard, alkaline water, roughly pH 7 to 8, anywhere from 20 to 28 C. They are easy eaters that take quality flake or pellet with some vegetable matter and the odd frozen treat. Because they breed so readily, expect fry, and provide plants for the babies to hide in.

In the wild

Green swordtails come from warm rivers, streams, and springs in Mexico and Central America, often in flowing water with plenty of plants. They like harder, alkaline water and a fair bit of swimming room. Give them a roomy tank with planted edges and open space in the middle, plus moderate flow that mimics their stream habitat.

Good to know

Xiphophorus hellerii is a livebearer in the family Poeciliidae. It is fairly large for a community fish, with males reaching about 15 cm including the long sword extension on the lower tail fin. Females are larger bodied but lack the sword. They bear live young rather than laying eggs, and females can store sperm to produce several broods from one mating.

Did you know

Females sometimes go through a sex change. A mature female can develop male features, including a sword and the ability to father young, usually when no males are present. It is a known quirk of the species and not a disease or defect.