Common Platy

Males reach about 5 cm, females grow larger to around 7 cm. Males have a gonopodium, a modified anal fin used for fertilization. The wild platy has a compact body and drab grey-silver colouring, sometimes with irregular black spots. Captive-bred varieties and hybrids show remarkable diversity in colour, pattern and fin shape.

Wild populations live in many river systems of Central America, from Mexico to Nicaragua. They prefer shallow backwater areas in rivers, lakes, marshes, canals and flooded pastures, particularly where dense aquatic plants grow.

Common platys are peaceful and active fish that need suitable tank mates. Males tolerate each other well, but groups with more females than males are preferable. They coexist well with close relatives such as swordtails and guppies, and with many other fish of similar size and temperament.

The platy adapts to a wide range of water chemistry, making it one of the most undemanding aquarium fish. Even a small tank with a simple air-lift filter will work if not overstocked. In such conditions, change 30–50% of the water every two weeks to maintain the balance. Provide hiding places among plant clumps and other décor. Driftwood, branches and roots are welcome additions; algae grow well on them in bright light and make a good supplement to the fish's diet.

These fish eagerly eat all food types: dry food (flakes, pellets), frozen and live foods such as bloodworm, daphnia and brine shrimp. Feed them once or twice daily, offering only what they can consume in five minutes. Remove any uneaten food promptly.

Breeding requires no special conditions. With a mature male and female present, fry will appear regularly, every one to two months. A single female may produce up to 80 fry. Remove the fry to a separate tank immediately to prevent the adults from eating them. A 3-litre jar is sufficient. The water parameters in the nursery tank must match those of the main tank.

The platy's hardiness depends on how close a hybrid or selectively bred variety is to its wild ancestors. Disease is uncommon when conditions are good.

When buying platys, look for active fish showing interest in their surroundings and food. Avoid those with scale damage, torn fins, a swollen belly or white spots. Check the shop tank: water should be clear and odourless, with no dead or obviously sick fish. Remember that platys are livebearers, so plan the sex ratio of your group in advance, preferring more females than males to reduce stress.