Sanke Swordtail

The Sanke Swordtail is a selectively bred form of Xiphophorus hellerii and does not occur in nature. The body displays the Koi pattern: a combination of white and red (orange) with black spots or irregular markings. The pattern is unique to each individual. Sexual dimorphism is pronounced: males have the characteristic elongated lower ray of the tail fin, called the sword, and a slimmer body. Adult fish reach 14–16 cm.

This is an artificially bred form and has no natural habitat. The parent species, Xiphophorus hellerii, inhabits Atlantic river systems in Central America (Mexico, Guatemala, Honduras). In nature these fish live in clear waters with moderate flow and abundant vegetation, preferring areas with sandy or rocky bottoms.

These are active and peaceful fish suitable for a community tank. They get along well with similarly sized non-aggressive species. Aggression between males can occur, so it is best to keep them in groups with more females than males (ideally 1 male per 3 females). The fish occupy mainly the middle water level.

These fish are highly adaptable and undemanding. The Sanke Swordtail can thrive across a wide range of temperatures and water chemistry, including brackish water. Tank setup requirements are minimal. To keep them healthy, perform weekly partial water changes, regularly remove uneaten food and waste, clean algae from the glass, and maintain equipment. A cover is recommended to prevent jumping; dense floating plants also help. As for diet, Sanke Swordtails are omnivorous and eat most aquarium foods. Daily feeding can be based on quality flakes or pellets, with live or frozen foods as a supplement. In behaviour and compatibility, Sanke Swordtails are active and friendly. They are peaceful toward their own kind and other species, coexisting well with non-aggressive fish of comparable size. However, note that they can produce hybrid offspring when crossed with other swordtail varieties and related species such as platies and mollies.

Omnivorous. In the aquarium they take any quality flakes or pellets. To maintain health and colour, supplement the diet with live or frozen foods (brine shrimp, daphnia, bloodworm) and plant matter such as spirulina or blanched vegetables. Feed once or twice daily in small portions.

Livebearing species: females give birth to fully formed fry. Sexual maturity arrives early. Spawning can occur in the main tank, but for fry survival, a breeding tank with dense plant growth or floating plants is preferable, where young can hide from adults. Pregnancy lasts 4–6 weeks; a single brood can number 20 to 100 fry.

Fish health depends directly on water quality and balanced feeding. Poor conditions can lead to swim bladder disease, bacterial infections such as aeromonosis, and parasitic infestations. Prevention includes regular water changes, monitoring water parameters, and quarantine for new fish.

When buying, choose active fish with clean scales free of visible damage, sores or coating. Fins should be spread, breathing steady. Avoid fish showing signs of malnutrition, a sunken belly, or abnormal behaviour such as constant hovering at the surface or bottom. It is best to buy from reliable breeders, as colour intensity can vary.