The Swordtail fish belongs to Genus Xiphophorus Helleri and is usually found in Southern Mexico and Guatemala area. The males of the breed may grow up to 4 inches or 10 cm in length excluding their sword, and females up to 4.7 inches or 12 cm in length. Looking at its length a tank size of minimum 24 inches or 60 cm (a 20 gallon fish tank) should be selected. Swordtails prefer water temperature ranging between 70 – 79 F or 21- 26 C. Its diet includes Crustaceans, insects, worms, plant matter and dried food. Swordtails prefer medium-hard and slightly alkaline water and they breed live babies.
The swordtail is slender in shape, and laterally compressed. It is so called a swordtail because the male has a long sword at the bottom of its tail. The females of the breed do not have this sword. They are often compatible with other fishes but when it comes to adjusting with smaller fish, they have been known to get slight aggressive. This is especially seen when the tank size is smaller. So, when deciding companions for the Swordtail, one should always take some care.
Swordtails have been breed successfully in captivity just like the platy, resulting in a variety of color form, but the red color is most common and popular. The variety has also been found with lyre-shaped tails and either an upper or lower sword.
The male and female Swordtails are easily distinguished as males have a modified anal fin which is called a gonopodium. Females rarely have a modified anal fin. When breeding, the mother swordtail may give birth to 20 – 100 young ones at a time, after a gestation period of four to six weeks. The young Swordtails are seen swimming freely after birth and grow rapidly.
It is often preferred to shift the mother to a smaller aquarium at the time of birth. If there are sufficient plants in the tank, a few young ones may survive in the community, but most of them would still be eaten by the other occupants of the aquarium.