How to Tell the Gender of My Platy

Platy fish, also known as moonfish, are a small live-bearing fish native to North and Central America. Common as freshwater tank pets, platy reach maturity in three or four months and will breed regularly. With females carrying between 20 to 40 eggs at a time, it can be quite the surprise to wake up to many more fish in your tank than you had the night before. You can prevent unwanted pregnancies by sexing and separating your fish.

Instructions

    • 1

      Isolate each fish in a small container of water.

    • 2

      Look at the shape of each fish. Female platy will be longer than male platy and will have wider stomachs, even if they are not carrying eggs.

    • 3

      Looking at the fins along the underside of the fish. Each fish should have three fins along its belly, with female fish having three almost identical fins and male fish having two flat fins with the aft fin being smaller and pointed.