How to Tell the Difference Between Male & Female Molly Fish

Molly fish are small tropical fish that can come in a wide range of colors. They are popular fish for aquarium keepers of any level, and some of the most popular varieties include the dalmatian molly fish and the balloon molly fish. If you have an interest in breeding molly fish, being able to distinguish between male and female molly fish is essential. Even if you don't want to breed them, being able to tell the difference between males and females is useful, and̵2;once you know what to look for̵2;it's easy to do.

Instructions

    • 1

      Wait until the molly fish is about 2 months old. Molly fish live for 3 to 5 years, and and you will start to notice secondary sex characteristics between the ages of 2 to 3 months.

    • 2

      Look at the anal fin. The anal fin on a molly fish is located on the belly of the fish; it's the fin closest to the tail. On a male, the anal fin is elongated and tubular in shape. This is because the anal fin on the male contains an organ that is meant to deposit sperm in the female. The female's anal fin is fan shaped.

    • 3

      Examine the body shape. The body of a female molly fish in profile is rounded than that of the male. The male tends to have a body that is slightly longer and thinner.

    • 4

      Inspect the coloration. In most types of molly fish, the males are more brightly colored and showy than the females. That means that although both male and female might be orange, the male is a more vibrant hue.