Swordtails are lively livebearers from Central America, named for the long blade extending from the lower tail of mature males.
Closely related to platies, they are larger, more active, and need more swimming room than their compact cousins.
Hardy and adaptable, they come in red, green, pineapple, and tuxedo varieties.
They are strong swimmers and accomplished jumpers, so they suit keepers who provide length, a secure lid, and stable, slightly hard water.
Housing
Their size and energy call for a tank of at least 95 litres (25 gallons) with good length, kept at 22-28C (72-82F) in hard, alkaline water and filtered to keep nitrate low.
Open swimming space matters more than height for these powerful swimmers.
A tight-fitting lid is essential, as swordtails are notorious jumpers.
Provide planting at the sides and back for cover and fry refuge while leaving the central water column clear for their constant activity.
Diet
Swordtails are omnivores that do best on a varied, vegetable-inclusive diet.
Use a quality flake or pellet base, add spirulina, algae, and blanched greens, and offer frozen or live foods such as bloodworms, daphnia, and brine shrimp several times a week.
Feed modest amounts once or twice daily, only what is consumed quickly.
Like other livebearers they tend to overeat and can become constipated on a low-fibre diet, so keep vegetable matter a regular part of the menu.
Health
Swordtails are robust given clean, hard, stable water, but suffer ich, fin rot, and constipation under neglect or poor diet.
Steady warmth, strong filtration, and weekly water changes prevent most disease in this hardy species.
Mass-bred stock can be genetically weaker, so source carefully and quarantine new fish.
Watch for clamped fins, white spots, or a swollen belly with stringy faeces, signs of parasite or dietary trouble that respond to corrected care.
Temperament
Swordtails are active and largely peaceful, but mature males can be territorial toward each other, sparring over space and females.
Keeping a single male, or several with plenty of room and a female-biased group, reduces conflict and stress.
They are confident, outgoing community fish that occupy open water and rarely hide.
As ready breeders, mixed groups produce frequent fry, which adults will eat unless dense planting offers the young somewhere to shelter.
Beginner
Beginner
Beginner
Beginner
Beginner
Beginner