How to Tell the Difference Between Male and Female Guppies

One of the more popular choices for home aquariums, guppies require basic care and thrive in a variety of conditions. Breeding these live-bearing fish is simple--just place males and females together, no complex set-up is needed. When purchasing guppies for your aquarium, you can easily identify the differences between males and females.

Instructions

    • 1

      Female guppies are larger, less colorful fish, while males are smaller and brightly colored.

    • 2

      Inspect the caudal, or tail fin, distinctly defined by size in males and females. While both male and female caudal fins appear fan-shaped, the male's fin is much larger, more colorful, and has a flowing appearance.

    • 3

      Notice the size and shape of the anal fin in both sexes, located approximately mid-way down the underside of the body. Females have a distinct fan-shaped fin, while males display a sword-shaped fin (gonopodium) used in mating.

    • 4

      Note the size of the dorsal fin, located parallel to the anal fin, on the top side of the body. Males have a larger dorsal fin than females.