Swordtail care guide
Swordtail (Xiphophorus hellerii) — minimum tank 75 L, temperature 22-28 °C, pH 7-8.
Compiled by Aquairi from published sources · Published · Updated
Overview
The Green Swordtail (Xiphophorus hellerii) is a hardy livebearer native to Central America, with mature males developing a distinctive elongated lower caudal fin lobe — the “sword”. Many selectively bred colour and finnage varieties are available in the trade.
Taxonomy
- Family: Poeciliidae
- Genus: Xiphophorus
- Scientific name: Xiphophorus hellerii
- Common synonyms: Green Swordtail
Habitat
Wild populations occur in warm, moderately flowing streams and rivers from southern Mexico through Guatemala, Belize and Honduras, in habitats with hard, slightly alkaline water and dense vegetation.
Tank requirements
- Minimum tank volume: 75 L (19.8 US gal)
- Adult size: 8-12 cm
- Temperature: 22-28 °C (72-82 °F)
- pH: 7-8
- GH: 12-25 °dGH
- Water flow: moderate
- Lifespan: 3-5 years
Diet
An omnivore. Offer a quality flake or pellet diet supplemented with vegetable matter and occasional live or frozen foods (daphnia, brine shrimp). The species also grazes on algae.
Compatibility
A peaceful community fish. Keep one male with two or more females to spread male attention. Compatible with platy, molly, peaceful tetras and Corydoras. Avoid keeping with very aggressive species or those needing very soft, acidic water.
Breeding
A prolific livebearer; females give birth to 20-80 free-swimming fry every four to six weeks. Provide floating plants or a separate nursery to improve fry survival.
Breeding Swordtail
Overview
The Swordtail (Xiphophorus hellerii) is a livebearer rated beginner-level for breeding and is described as one of the easiest fish for amateur aquarists to breed when both sexes are kept together in suitable conditions.
Sexing
The female is larger than the male but lacks the sword, the elongated extension on the lower tail fin that males develop. Males also possess a gonopodium, a modified anal fin used to impregnate the female. A dark gravid spot develops near the female's anal fin during later pregnancy.
Conditioning the Breeders
The presence of a well-developed male spurs the maturity of females while inhibiting the maturity of nearby juvenile males. A ratio of one male to three or four females is recommended so that individual females are not overly harassed.
Spawning Behavior & Birth
Swordtails are live-bearers that give birth to fully formed fry rather than laying eggs, the male fertilising the female internally with the gonopodium. Breeding occurs readily when proper tank conditions exist and both sexes are present, which is why the species is regarded as one of the easiest for amateur aquarists to breed. A dark gravid spot near the female's anal fin during later pregnancy signals an approaching birth.
Fry Care
Fry require shelter, as they will be eaten by other aquarium inhabitants if they cannot find cover. Dense planting or a separate grow-out container greatly improves the share of each brood that survives. The young reach sexual maturity at around three months of age, so successive generations can appear in quick succession.
Common Challenges
Predation of fry by tankmates is the main loss, so dense planting or a grow-out space is advisable. An unbalanced sex ratio can lead to excessive harassment of females, which is why a ratio of one male to three or four females is recommended; the presence of a well-developed male also spurs the maturity of females while inhibiting the maturity of nearby juvenile males.