Fish, Tanks and Ponds

Fish, Tanks and Ponds
A comprehensive guide to fish

Xiphophorus. sp


Platy, Xiphophorus. spPlaty, Xiphophorus. sp
Photos by Andy Rapson


Xiphophorus: Greek, xiphos = sword + Greek, pherein = to carry.

Refers to swordtail fish of this genus.

General Notes:

The fish which is now referred to as a platy is a hybrid of two species which have been cross bred for so long that they are almost indistinguishable from each other. The true species of either fish is only very rarely available. Platies come in a wide range of sizes shapes and colours all of which have been line bred for the aquarium trade. Platies prefer a pH of 7 and over but as long as extremes are avoided they should adapt quite well although they may do less well in very acidic water. Platies are ideal fish for the beginner because they are so adaptable and hardy and above all they are very peaceful with other small community fish.


Wild platies feed on algae, tender plants, insect larva, crustaceans, worms and molluscs. In captivity they will readily accept flake food, suitably sized pellets or granular fish food, freeze dried, frozen and live food. They are generally quite bold feeders and should present no problems.


Male platies have a gonopodium to allow internal fertilisation while the females have an ordinary looking anal fin. Females tend to be larger but this cannot be relied upon because different varieties of platies can be different sizes and because of all the cross breeding some male platies are larger than females.


Platies are livebearers which means that they don't lay eggs at all, instead the eggs are retained inside the female until they have hatched and the fry have absorbed their yolk sacs. When the fry are 'born' they are very well developed and free swimming immediately and fully independant. Male platies can be a nuisance to the females because of their persistent attention, to help prevent a female from being bullied and pestered by the males it is better to keep two or three females for each male, that way the attention of the male is spread more widely. Platies don't need any special treatment in order to get them to breed, simply housing a healthy well cared for pair together is all that is required.

The fry are very small when first born and if they are born in a community tank they will be eaten by the other fish. Ideally a separate nursery tank should be used which is filtered with a (mature) sponge filter and well planted (Indian fern, Ceratopteris thalictroides)  is ideal for this because it floats on the surface and sends down lots of roots where the fry can hide. Once the fry have been born the female should be removed and the fry left in their own tank. The fry can be fed on cyclops, newly hatched brine shrimps and finely crushed flake food, with good care they will reach sexual maturity within twelve weeks although once they reach around 2.5cm (1in) they will be safe with other small community fish.

Breeding traps are still sold but are far from ideal for either the pregnant female or raising the fry. These things are not recommended.

Wild status

Platies are widespread and common. They have become a pest in some regions due to their very prolific nature.

Information at a glance

pH: 7 - 8
dGH: 9 - 19
Temperature: 22 - 28°C (72 - 82°F)
Diet: Omnivore
Size: 4 - 7cm (1.5 - 2.8in)
Min tank size: 60 litres
Difficulty level: Easy
Aquarium type: Community
Swimming level: All levels

Distribution and habitat

distribution map for Platy, Xiphophorus. sp

Origin: North and Central America: Ciudad Veracruz, Mexico to northern Belize. Introduced to other Countries where they have been reported as being pests by adversely affecting the native habitat.

Habitat: Still or slow moving water with lots of plant cover.


Kingdom: Animalia
Phylum: Chordata
Class: Actinopterygii
Order: Cypridontiformes
Family: Poeciliidae
Genus: Xiphophorus
Species: X. maculatus and X. variatus

Common name:

Synonyms: X. maculatus: Platypoecilus aurata, Platypoecilus cyanellus, Platypoecilus maculatus, Platypoecilus maculatus aurata, Platypoecilus maculatus cyanellus, Platypoecilus maculatus sanguinea, Platypoecilus nigra, Platypoecilus pulchra, Platypoecilus rubra, Platypoecilus sanguinea, Poecilia maculata.
X. variatus: Platypoecilus variatus.