About Swordtail Fish

About Swordtail Fish

Origin and Distribution

Swordtail fish have been a vibrant component of the aquarium hobbyists community for many years. Originating from Mexico and Central America, the Swordtail has been bred in captivity for countless generations. There are many varieties widely available to the aquarium community, including the naturally colored green swordtail, as well as neon, pineapple, painted, marigold wag, red wag and hi fin lyretail.


  • Approx. size: 2-5cm
  • Maximum size: 8cm
  • Origin: Mexico/Central America
  • Ideal number kept together: 3+
  • Family: Poeciliidae
  • Social: Peaceful
  • Tank Level: Top, mid-dweller
  • Care Level: Easy
  • Breeding: Live-bearer
  • Diet: Omnivore
  • SCIENTIFIC NAME: Xiphophorus helleri

Water conditions

  • pH: 6.0–8.0
  • Hardness: 90–447 ppm
  • Temp: 23-28°C
  • Minimum tank size: 20 Gallons

Ease of care
Easy. The sexes will need to either be kept separately or 2 females to every 1 male. They will harass the females otherwise.

Over several generations, you may note an increase in your fry deaths, or your fish may not live as long. If you continue to breed the same populations, you can expect to have health issues resulting from inbreeding . The best fix for this is adding a little genetic diversity through the purchase of new fish or trading with another hobbyist. Unless you know your new fishes' health history, before adding them to your aquarium it is always recommended to quarantine your new fish yourself.


Swordtails are omnivores that enjoyed a varied diet. Depending on the water temperature, you may need to feed your fish 2-3 times per day. Many tropical fish like to forage throughout the day, so fewer feedings are not ideal for swordtails. Swordtails do well on most community micropelleted diets or tropical flake, and also enjoy occasional frozen and freeze-dried treats.


A community aquarium with no fin nipping fish.

Swordtails do best living in a group, so plan on at least 4-5 individuals per aquarium. You are welcome to mix different varieties together, but be ready for a swarm of baby swordtails if you mix males and females. Being live-bearing fish, swordtails can reproduce very quickly, reaching sexual maturity as early as three months of age. Some potential tankmates include Neon Tetras, Coolie Loach or Corydoras.

Swordtails do well in many different aquarium setups. These easy going fish are good for beginners and a colorful addition to any community tank. They are active fish, so make sure there are not too many decorative items in their way. The best combination for swordtails is to keep your décor and plants to the lower half to 2/3 of your tank and leave the top of the tank open for active swimming.

Male swordtails may take up territory and become aggressive towards other fish. Be sure to have plenty of room for all your swordtails, despite their small size! It may help to add fake or live plants to give your fish more hiding areas.

Breeding/ Sex

Livebearer fish, such as swordtails, can easily over populate an aquarium. Many beginners are not aware of the swordtail's livebearing abilities and are suddenly surprised by a swarm of baby swordtails. Many swordtail owners start with just a few swordtails, not realizing that the females may be pregnant when acquired. Even one pregnant swordtail may surprise a novice fish owner with a sudden population explosion.

Swordtails have specific characteristics to easily differentiate male and female fish. Males have the characteristic "sword" on the ventral aspect of their tails. Females have a rounded tail edge and tend to have thicker bodies. This comes from carrying all their live baby fry. The anal fin is also pointed in males and fan-shaped in females. This can be used to determine gender in young fish before the males develop their long sword tail.

Swordtail male and female
Swordtail male (top) and female (bottom) 

Swordtails can become mature as early as 3 months old and birth up to 50 fry per spawning. If you don't want more baby swordtails, it is critical that you separate males from females before they reach reproductive maturity. As previously noted, males have the distinctive "sword" on the ventral aspect of their tail fin, and an elongated anal fin, making the identification easy.

Life Span

They can live to anything from 1-5 years in perfect conditions.

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