What tank size does a Swordtail need?

A Swordtail needs an aquarium of at least 90 litres (23.8 US gallons) with a footprint at least 90 cm (35.4 in) long — for this species, swimming length matters as much as raw volume.

What water parameters does a Swordtail need?

Swordtail does best at 22–28 °C (71.6–82.4 °F), pH 7–8.4 and a general hardness of 12–30 °dGH.

What group size does a Swordtail need?

Swordtail is a social species — keep a group of at least 6 so natural behaviour emerges and stress stays low.

Is the Swordtail suitable for beginners?

Yes — Swordtail is one of the easier species to keep and forgives typical first-tank mistakes, as long as the aquarium is cycled and maintained.

Species library

Swordtail

Xiphophorus hellerii

Poeciliidae

FishDifficulty: ●●○○○Data: well-established

📷 Corydoras-adolfoi · CC BY-SA 4.0 · resized · Wikimedia Commons

Swordtail — Xiphophorus hellerii — 📷 Corydoras-adolfoi · CC BY-SA 4.0 · resized · Wikimedia Commons

About

The swordtail is a lively, robust livebearer from Central America, named for the elongated lower tail lobe (the 'sword') carried by mature males. Wild fish are green-flanked with a red lateral stripe, while aquarium strains offer red, orange, black, pineapple and lyretail forms. Larger and more energetic than platies, swordtails are strong swimmers and accomplished jumpers, so a long, well-covered tank is essential. Males can be scrappy with one another, so keep a single male or a female-dominant group to spread aggression.

Care

Provide a long, covered 90 cm+ tank with hard, neutral-to-alkaline water 22-28°C. Keep one male or several females per male; strong swimmers and jumpers.

Diet

Omnivore; varied flake/pellet with vegetable matter plus live/frozen protein.

Tankmate compatibility

Computed by the AquaSage engine for a spacious reference tank — always check the full verdict for your exact setup in the calculator.

Full tank-mates guide with reasons →

Telling males from females

What works for this species, most reliable first.

The gonopodiumDefinitive · from about 4 weeks old
Look at the anal fin, underneath and just behind the belly. In females it stays a broad triangular fan. In males it narrows into a rod and angles forward — that rod is the gonopodium, a rebuilt fin rather than an organ that appears from nowhere.

All the methods, with diagrams

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Frequently asked questions

What tank size does a Swordtail need?: A Swordtail needs an aquarium of at least 90 litres (23.8 US gallons) with a footprint at least 90 cm (35.4 in) long — for this species, swimming length matters as much as raw volume.
What water parameters does a Swordtail need?: Swordtail does best at 22–28 °C (71.6–82.4 °F), pH 7–8.4 and a general hardness of 12–30 °dGH.
What group size does a Swordtail need?: Swordtail is a social species — keep a group of at least 6 so natural behaviour emerges and stress stays low.
Is the Swordtail suitable for beginners?: Yes — Swordtail is one of the easier species to keep and forgives typical first-tank mistakes, as long as the aquarium is cycled and maintained.

Sources

Water & tank

Temperature22–28°C

Optimal temp.23–26°C

pH7–8.4

Hardness (GH)12–30°d

Carbonate (KH)6–18°d

Adult size14 cm

Min. volume≥ 90 L

Min. tank length≥ 90 cm

Group size≥ 6

Swimming zoneMid

TemperamentPeaceful

Water typeBrackish-tolerant

FlowModerate

Lifespan~4 yrs

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