Max Size: 10cm

Swordtail (Xiphophorus helleri)

Swordtails have to be one of the most popular aquarium fish. The Green Swordtail has been bred into several hybrid forms for the aquarium hobby due to its hardiness and adapting to many different water parameters, making them an excellent choice for beginner aquarists.

Swordtails are an active and peaceful fish that works well in a community tank with other small peaceful fish, and you can keep them in a species only tank. However, Swordtails can become nervous when kept with more extensive, boisterous fish, hiding away amongst the plants and decorations.

These fish live in groups but are not a shoaling fish and are best kept in groups of 5 or more, making sure there are more females than males as the males can be aggressive towards one another.

Swordtails' wild form is olive green in colour, with a red or brown lateral stripe and speckles on the dorsal and occasionally, caudal fins. These fish are best known for the unique, attractive tail that is yellow and edged in black below, although only males possess this.

Captive breeding has produced many colour varieties, including black, red, as well as various patterns for the aquarium hobby; still, they all originate from the wild green form.

Quick Facts
Scientific NameXiphophorus helleri
Other NamesRed, Green, Tuxedo, Koi, Lyretail, Black, Hi-fin, Neon
OriginsGuatemala, Honduras, Mexico
Aquarium LevelMiddle - Top
DifficultyBeginner - Intermediate
Best kept asGroups 5+
Lifespan3 - 5 years
Water Parameters
Water TypeFreshwater
PH7.0 - 8.5
GH12 - 30
65 - 82℉
18.3 - 27.8℃


Black Swordtail
Green Swordtail
Lyretail Swordtails
Wild Type Swordtail
Black Swordtail

Natural Habitat

Swordtails are native to Veracruz, Mexico, Guatemala and northwestern Honduras in North and Central America. They inhabit fast-flowing streams and rivers as well as pools, canals, and even warm springs.

They have a liking for some vegetation, on which they often graze, but this doesn't mean they need a densely planted tank. These fish are rarely found in woody areas or those with high quantities of leaf litter. The preference is for clearer substrates, sandy, rocky, and light, although sometimes with mulm and debris providing it can settle in fast-flowing waters.


Swordtails are not fussy and will eat virtually anything. In their natural habitat, these fish eat a lot of algae and other vegetation.

In captivity, you should give them high quality dried foods such as flakes, granules, pellets and algae wafers, as well as good quality frozen and live foods such as brine shrimp, mosquito larvae, fruit flies, bloodworm and daphnia.

Ensure you supply them with an ideal mix of protein and vegetation to satisfy their exact diet needs perfectly. Feed your Swordtails two or three times daily. They don't require much food, just what they can consume within a few minutes. Remember to remove any leftover food, so it does not pollute the water.

If you stick to a routine, your fish will soon learn when to expect food and become much more active at feeding times.

Sexual Dimorphism

It is effortless to determine the male from female Swordtails. A Gonopodium's presence can distinguish males, a modified anal fin used to impregnate females during breeding.

Also, a male's caudal fin sticks out from its lower half, the extent of which may reach half of the body's entire length. The female caudal fin has no such protrusion. Also, females are usually much larger than males.


Swordtails are some of the simplest fish for the amateur aquarist to breed. If the tank's conditions are appropriate, and the tank contains both males and females, reproduction will occur without intervention.

Often all-female groups from a mixed-gender tank will already be pregnant on arrival, forming a breeding population when the fry reaches sexual maturity around three months of age. Later pregnancy stages can be seen without much difficulty as a dark gravid spot will develop near the anal fin.

It would be best if you kept a ratio of one male to three or four females to ensure that males will not overly harass individual females to breed. Plants and other structures in the aquarium will offer fry a place to hide after birth. This is important as the newborn fry will be eaten by other aquarium inhabitants if they cannot find shelter. Alternatively, you can set up a separate grow out tank and place the fry in there to increase fry survival.

The baby Swordtails search for food as soon as they are out in the water. You can provide them with newly-hatched brine shrimp and finely crumbled flakes as their first food until they are big enough to eat the same as the adults.

Growth for swordtail fry is relatively slow. If you would like the fry to grow faster, you should perform water changes frequently and provide a good quantity of meat.

Other Livebearers of interest

Cardinal Brachyrhaphis(Brachyrhaphis roseni)
Dusky Millions Fish(Phalloceros caudimaculatus)
Humpbacked Limia(Limia nigrofasciata)
Merry Widow Livebearer(Phallichthys amates)
Mollies(Poecilia Sphenops)
Platies(Xiphophorus maculatus, Xiphophorus variatus)
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Date Added: 22/01/2021 - Updated: 19/01/2022 14:56:06