Swordtail Basics

[KingOfSwords]

The Swordtail, usually identified as Xiphophorus helleri, is one of the most popular of the livebearing fish in the hobby today. Along with the two species that are sold as "Platies", they come from a genus that is widespread throughout Mexico, and into Guatemala and Belize. Swordtails are primarily found in rivers and streams, though some populations also occur in large lakes. Therefore, good water quality is of great importance for their continued health and well-being.

Like most of the common Livebearers, they prefer moderately to very hard water. Swords are better off at lower temperatures than one might think, from about 68 to about 74, though they will live quite well up to about 82. To keep them properly requires a minimum of a 30 inch long tank, and a good cover, as they are excellent jumpers. Some algae in their diet seems to help the color, and keeps them healthier. However, they will also eat anything that happens to come within view; flakes, pellets, frozen, and live foods are all taken with gusto.

Swordtails can attain a much greater size than normally seen in the hobby. Most stores carry 3 inch body size fish as "large", but in the wild they can reach 6 inches! There are some related species that get even larger.

Mature Male Swords are easier to sex than other livebearers, because they have the obvious extension of the lower part of the tail (the "Sword") in addition to the usual modified anal fin, or Gonopodium. In the wild, males defend a territory, trying to mate with the schools of females that enter it, and chasing away rival males. These territories can be quite large, so keeping more than one male in the average aquarium is not recommended. Only in larger tanks will additional males be safe.

There are many color varieties of Swordtails in the hobby today, as well as a couple of fin types. Much of this comes from crossing the original species, Xiphophorus helleri, with other species of the same genus, especially X. maculatus, the common Platy. The fact that they will readily interbreed should be remembered if one is considering combining the two species in a community aquarium. Crossing with Variatus Platies, X. variatus, can also occur.

Attached photos are a Red male and female for comparison of sexes, and a 4 inch body Black Hi-fin Lyretail Sword to show what careful breeding can produce.