Swordtail Identification

Swordtails are attractive tropical fish that inhabit Central America. The males possess an impressive sword-shaped extension to their caudal (or tail) fin. This sword, which is typically longer in wild strains, is between one-quarter and one-third the length of tank-bred specimens. Male swordtails have a highly modified anal fin, known as a gonopodium, through which they inseminate female fish. Female swordtails have larger abdomens to accommodate the developing embryos. Swordtails are available in a number of varieties in many colors, sizes and fin types. Aquarists introduced swordtails to the hobby prior to 1864 and they have remained a well-known and easy-to-breed aquarium fish.

  1. Wag and Black Swordtails

    • Swordtail enthusiasts continue to hybridize these well-liked tropical fish. Certain crosses are accidental, as swordtail can hybridize with other livebearers in a community aquarium. Established strains include the wag swordtail and black swordtail. Wag swordtails are available in both red and gold with contrasting black fins. Black swordtails are attractive, little tropical fish, and are calmer than many of the other swordtail strains. Select black swordtails have impressive metallic blue spots.

    Red Velvet Swordtails

    • The red velvet swordtail is a hybrid between red platys and green swordtails. This beautiful fish has a velvet-like sheen. Male red velvet swordtails are aggressive toward other males -- particularly platys -- during spawning. Like all swordtails, the red velvet is omnivorous, but readily accepts a high-quality flake food.

    Painted Swordtails

    • The painted swordtail is a more recent and dramatic color variation of the swordtail. This swordtail strain, which is available in a red, green or gold coloration, has interesting dark markings on the back half of its body. These curious black patterns give the appearance that paint was splashed on the fish.

    High-fin and Lyretail Swordtails

    • High-fin swordtails have elongated dorsal, pectoral and anal fins. Their caudal or tail fin, as indicated by their common name, is particularly impressive; the combined visual effect is quite stunning. The particularly long fins of these fish sometimes hinder the mating process and high-fin swordtails are not easy to breed. Lyretail swordfish have an enlarged sword on their caudal fin, often half the length of their bodies. The lyretail is a very peaceful swordtail strain and other fish can easily dominate it in a community aquarium. Many breeders hybridize high-fin swordtails with lyretail swordtails to produce a graceful and beautiful fish, which is available in a number of color variations.