Swordtails are hardy, active livebearers named for the sword-like extension on the male’s tail. Closely related to platies, they are slightly larger and more energetic, and they thrive in the hard water that comes out of most UK taps — making them an excellent, colourful choice for a community tank.
Here is how to keep them.
- Swordtails are hardy, active livebearers that thrive in hard UK tap water.
- They need a longer 90-litre-plus tank with a secure lid — they are keen jumpers.
- Keep two to three females per male to spread breeding attention.
- Multiple males may spar, so keep one male or a larger diffusing group.
Quick facts
- Adult size: 10–13 cm (including sword)
- Tank size: 90 litres minimum
- Water: pH 7.0–8.4, hard, 22–28 °C
- Lifespan: 3–5 years
- Temperament: peaceful but active; males can spar
Tank setup
Swordtails are strong swimmers that need a longer tank of at least 90 litres with a secure lid — they are notorious jumpers. They enjoy planted tanks with open swimming space and moderate flow, and appreciate the hard, alkaline water typical of UK supplies. Keep a heater at 24 °C.
Feeding and breeding
Feed a varied omnivore diet with a vegetable lean — quality flake, algae-based food and frozen treats. Like all livebearers, they breed readily; keep two to three females per male to spread male attention. See livebearer breeding.
Tank mates
Good tank mates: platies, mollies, danios, corydoras, peaceful barbs. Keep only one male, or a group large enough to diffuse sparring between males.
Frequently asked questions
What size tank do swordtails need?
At least 90 litres. They are active swimmers reaching 10–13 cm including the sword, so they need more length than smaller livebearers.
Do swordtails need a heater?
Yes — they are tropical and need stable water of 22–28 °C, so a thermostatic heater is essential in UK homes.
Do swordtails jump out of tanks?
Yes, they are well-known jumpers. Always keep a secure, well-fitted lid on the aquarium.
— Jaqline Smalling, FishForever
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