Swordtails require a tank that is a minimum of 3ft in length, and preferably longer, due to their eventual adult size. More streamlined and agile than platies, swords are often found in fast-flowing habitats and appreciate cooler water and high oxygen levels. They can be kept in community aquariums where no tiny fish are present, and they will appreciate plant cover. They also make excellent companions for smaller species of Central American cichlids such as Thorichthys and Cryptoheros in large aquaria, where they can avoid intruding on spawning territories. Males can become quite competitive towards one another, so it is wise to limit yourself to one male per tank in smaller set-ups. Larger groups are best with three or more males to spread aggression, outnumbered by females. There are numerous colour variants available and the wide selection often mirrors that of platies, due to their ease of hybridisation. Green forms, with or without black speckling, are closest to the wild fish and may be more tolerant of cooler temperatures. The fish pictured here is of the Pineapple variety.
Feeding
Swordtails will accept most foods offered. Try to ensure that they receive a good balanced diet of flake (standard and green) plus frozen foods such as mosquito larvae, brineshrimp and daphnia. Like platies, swords will graze algae and biofilm from live plants.
Breeding
Swordtails are livebearers, and when a mixed group is kept, females tend to give birth every 28 days or so. After insemination, the female will gestate for 24-28 days and produce up to 50 free-swimming fry. Females store sperm and a single mating will result in several broods. The adults will predate on the fry if not separated. However, a few will normally manage to survive onto adulthood when kept in a well planted aquarium with lots of natural hiding places. Providing seasonally cooler temperatures will slow breeding and provide a break for the females.