The popular aquarium varieties of the swordtail are far removed in appearance from their drabber-looking wild relatives, although both types give birth to live young.
The name “swordtail”was given to these fish due to the elongated swordlike extension on the lower part of the tail (caudal) fin of many males. This feature is also reflected in their scientific name, which comes from the Greek word xiphos, meaning “sword.” Females have rounded tails. As with other livebearers, female
