Swordtail - Xiphophorus hellerii

Scientific name: Xiphophorus hellerii

Common name: Swordtail

Family: Poeciliidae

Usual size in fish tanks: 10 - 12 cm (3.94 - 4.72 inch)

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Recommended pH range for the species: 7 - 8

Recommended water hardness (dGH): 12 - 18°N (214.29 - 321.43ppm)

0°C 32°F30°C 86°F

Recommended temperature: 21 - 28 °C (69.8 - 82.4°F)

The way how these fish reproduce: Pseudo-Livebearer

Where the species comes from: Central America

Temperament to its own species: peaceful

Temperament toward other fish species: peaceful

Usual place in the tank: Top levels

Feeding Swordtail Fish

Swordtails are omnivores and require a balanced diet to thrive. Their diet should include high-quality granules or flakes as a staple, but it’s important to supplement this with live or frozen foods. Suitable live or frozen options include bloodworms, brine shrimp, and daphnia. You should also provide vegetable matter, such as spirulina-based flakes or blanched vegetables (e.g., zucchini or spinach). This helps maintain their vibrant colors and overall health.

For the best results, feed them once or twice a day, and ensure they consume all the food within a few minutes to avoid excess waste. Overfeeding can lead to poor water quality and health problems.

How to Sex Swordtails

Sexing Swordtail fish is relatively easy once they reach maturity. Males are typically smaller and more slender than females. The key distinguishing feature is the male’s long, sword-like extension on the lower part of the tail fin, which is absent in females. Additionally, males possess a gonopodium (modified anal fin used for reproduction), while females have a standard rounded anal fin.

Females tend to be larger and bulkier, particularly when pregnant. Their larger size also allows them to produce and carry more fry.

Breeding Swordtail Fish

Swordtail fish are prolific breeders and are known for their continuous breeding cycle. They are livebearers, meaning the females give birth to live, free-swimming fry rather than laying eggs. If you have both males and females in the tank, they will likely breed without any intervention.

To encourage healthy breeding, maintain clean water and provide a well-balanced diet that includes live or frozen foods. Pregnant females will develop a dark gravid spot near the anal fin, indicating they are carrying fry. After a gestation period of about 28 days, the female will give birth to a brood of around 20-100 fry, depending on her size and age.

If you want to protect the fry from being eaten by adult fish, either provide plenty of dense plants for hiding or move the female to a separate breeding tank before she gives birth.

Lifespan

The average lifespan of a Swordtail fish in captivity is 3-4 years when kept in optimal conditions. Proper care, including regular tank maintenance, a healthy diet, and stable water parameters, can help ensure they live a full and healthy life.

Origin

Swordtail fish are native to Central America, specifically in regions of southern Mexico, Guatemala, and Honduras. In their natural habitat, they are found in rivers, streams, and heavily vegetated areas, which provide both food and shelter from predators.

Tank Setup and Conditions

Swordtails require a spacious aquarium with plenty of swimming room and some densely planted areas for shelter. A tank size of at least 100 liters (26 gallons) is recommended for small groups, but larger tanks of 200 liters (52 gallons) or more are better suited for maintaining a healthy and active group of Swordtails.

Maintain the water temperature between 21-28°C (70-82°F), with a pH range of 7.0-8.0. They prefer slightly hard water, with a water hardness (dGH) of 12-18. Providing good filtration and regular water changes is essential, as Swordtails produce a fair amount of waste. Strong water flow is also beneficial since they originate from fast-flowing streams.

Recommended Plants

Swordtails appreciate a well-planted tank for hiding spots and as areas to explore. Suitable plants include hardy species like Java Fern, Vallisneria, Anubias, and Amazon Swords. These plants can tolerate the slightly hard water that Swordtails prefer and provide plenty of cover for fry.

Compatible and Incompatible Tank Mates

Swordtails are generally peaceful and can be kept with other non-aggressive community fish. Suitable tank mates include:

Platies
Mollies
Guppies
Peaceful Tetras (such as Neon or Cardinal Tetras)
Corydoras Catfish
Otocinclus Catfish

However, they should not be housed with aggressive or fin-nipping species, as these fish can stress Swordtails or damage their flowing fins. Species to avoid include: