Assorted Swordtail fish 5cm (Xiphophorus helleri)

The time-tested popularity of the Swordtail can be attributed to its ease of care, peaceful temperament, and wonderfully diverse fin and color varieties. The male Swordtail is especially prized for its namesake feature, the showy extension on the lower part of its tail resembling a sword. Great fish for the beginner.  Adult size: 15 – 20 cm, min tank size 55 litres.

The Swordtail (Xiphophorus helleri) is perhaps the quintessential community aquarium fish. They are native to North and Central America, ranging from Mexico to Honduras. Here they live in rivers and streams with lots of plants. They are also known to tolerate brackish waters, so can be kept in low salinities. These fish are livebearers, which mean they retain their eggs inside their body and give birth to live young.  They are closely related to the Southern Platy and can even crossbreed with them. This crossbreeding has produced many varieties of aquarium fish.

Behaviour

They are hardy and easy to care for, making them a great choice for beginners.  They live in groups, but they are not shoaling fish. Males might show aggression towards each other, so make sure they are outnumbered by females in a ratio of 4 to 1.  As they prefer being in groups, each additional fish needs roughly 20-25 litres of water to keep them comfortable.  They occupy the middle and upper levels of the tank, rarely exploring down to the bottom. If given enough swimming space, they will be very active members of your aquarium.

Tank Conditions

Swordtails rarely venture to the bottom of the tank so for them the substrate doesn’t matter much. Use sandy substrates if you want to replicate their habitat as closely as possible.  Rocks and bogwood create a natural feel to your tank – they also make some useful caves and crevices too.

Plants are an important as they need to hide when they are feeling stressed. Spread them around the tank, but make sure to leave lots of swimming space.  There are so many plants to choose from. Anubias Nana, Java Fern, and Dwarf Hairgrass are some great options.

They are jumpers so always keep your tank covered.

Compatibility

Peaceful, active fish such as Swordtails pair well with other similar species. They are social fish that will enjoy the company of other passive tank mates.This is seen in the wild where they live alongside Platies, their close relatives. They mix well with with Mollies, Rosy Barbs, Neon Tetras, Dwarf Gourami, Pearl Danio, or Angelfish in the mid-levels of the tank.  Dwarf Corydoras, Kuhli Loaches, Otocinclus, and Zebra Loaches are good options for adding some activity to the lower levels.

Feeding

Your Swordtails will eat virtually anything, so it’s easy to design a suitable diet.  In the wild their omnivorous diet would include insect larvae, algae and other vegetation. You can give them high-quality dried foods to supply a range of nutrients. However, as juveniles they need lots of protein. This means that live or frozen foods like bloodworms, daphnia and brine shrimp are important supplementary items to a dried food diet.  Make sure that they receive some vegetation too (this will provide some fiber to ease their digestion) such as Algae wafers.

Care

Since most livebearers are hardy, they are not prone to disease, but they are not completely immune either. If you notice signs of disease, isolate the infected fish in a quarantine tank to prevent it spreading to the rest of your fish.

Swordtails are simple to care for and are hardy so they can usually survive most beginner mistakes.

See Fish Disease Diagnosis and Treatment at Rebel Pets for help with diagnosing and treating diseases.