Swordtail

Behaviour and habits

The swordtail is an active, hardy livebearer whose name comes from the long, sword-like extension on the male's tail. It swims at every level of the tank, is constantly busy, and breeds readily, so a mixed group soon produces young. Males chase females relentlessly, which is why the group should be skewed towards females, and the fish needs a tank with length rather than height so it can swim properly.

What to feed, and how often

A flake or pellet staple plus blanched greens and occasional frozen food works well. Feed twice a day, lightly, and include vegetable matter, since swordtails graze algae and benefit from greens. They are greedy eaters, so be careful not to overfeed and foul the water.

Water changes and maintenance

Change about 25% weekly in harder, slightly alkaline water, matched closely. Swordtails are hardy but dislike sudden changes and poor water; keep it clean, hard and steady for the best colour and health.

Care and how easy it is

Easy and hardy in harder water, provided the tank is large enough for it to swim and the sex ratio is right. It is a good beginner livebearer in the right setup.

Lifespan

With good conditions and steady water quality, this species typically lives around 3–5 years in a home aquarium; some individuals live longer.

Common health problems

Prone to fin rot and to 'shimmies' (twitching) when the water is cold or poor.

If it gets sick

Keep the water hard, warm and clean, and treat fin issues early with water changes, observing the group for a few days.