Swordtail Care Guide: Tank Size, Water & Tankmates
The swordtail (Xiphophorus hellerii) is a lively, colorful livebearer named for the long, sword-like extension on the lower tail of the males. Hardy, peaceful, and endlessly varied in color, swordtails have been a community-tank staple for decades and make a wonderful choice for beginners. At Tropical Treasures, we keep a rotating selection of swordtails in store, including the Tiger Swordtail, the Green Swordtail, and the Pineapple Swordtail. This guide covers everything you need to keep swordtails healthy and thriving.
Meet the Swordtail
Swordtails are livebearers native to Central America, closely related to platies and capable of interbreeding with them. Males grow the signature sword and reach about 4 inches, while females are a bit larger and lack the tail extension. They come in countless colors and fin types, from classic green to red velvet, tuxedo, and lyretail. They mix beautifully with platies, Endlers, and mollies.
Tank Size and Setup
Swordtails are strong, active swimmers, so they appreciate horizontal swimming space. A small group does best in a tank of at least 20 gallons, with more room for larger groups. Provide gentle to moderate filtration, open swimming areas, and some live plants for cover. A secure lid is important, because swordtails are accomplished jumpers.
Water Parameters and Heating
Swordtails prefer temperatures of 72–79°F, a pH of 7.0–8.0, and moderately hard, slightly alkaline water. A reliable aquarium heater keeps the temperature steady, which matters more than chasing an exact number. Always treat tap water with a quality water conditioner before water changes, and keep up with regular maintenance to keep nitrates low.
Feeding Your Swordtail
Swordtails are omnivores that enjoy a varied diet with plenty of plant matter. A quality flake or pellet fish food makes a great staple, supplemented with blanched vegetables, spirulina, and occasional treats like brine shrimp or daphnia. Feed small amounts once or twice a day, only what they can finish in a minute or two.
Tankmates and Temperament
Swordtails are generally peaceful and thrive in a community tank. Good companions include platies, mollies, guppies, tetras, corydoras, and other calm fish. Males can be a little territorial with one another, so either keep a single male or several, and maintain more females than males (about two to three females per male) to spread out attention and reduce stress.
Breeding Swordtails
Like other livebearers, swordtails breed readily and give birth to live, free-swimming fry. A female can produce 20 to 80 fry roughly once a month, and adults will eat fry if they can. Dense plants, a breeding box, or a separate grow-out tank all help fry survive. Feed fry finely crushed food or baby brine shrimp, and they will grow quickly. Be prepared to manage the population if you keep both sexes.
Is the Swordtail Right for You?
If you want an active, colorful, low-fuss fish that adds energy and elegance to a community tank, the swordtail is a fantastic pick, especially for newer hobbyists. Just give them swimming room, a secure lid, and clean, slightly hard water. New to the hobby and not sure where to start? Our guide on buying fish in store vs online explains why healthy, locally acclimated fish make all the difference.
Frequently Asked Questions
Do female swordtails have a sword? No. Only males develop the long sword-like tail extension. Females are larger and have a normal rounded tail, which is the easiest way to tell the sexes apart.
Do swordtails need a heater? Yes. Swordtails are tropical fish and do best with a stable heater keeping the tank in the mid-to-upper 70s°F.
How many swordtails should I keep together? Keep them in groups of at least four to six with more females than males. They are social fish that feel most secure in a small group with room to swim.