Here are the common ways to distinguish between male and female guppies:
I. Body Characteristics
Size Difference
Adult male guppies are usually smaller (about 3 cm), with a slender body and a thin waist; female guppies are larger (up to 5-6 cm) and have a round, plump abdomen.
Abdominal Gravid Spot
Female guppies have a distinct gravid spot on their lower abdomen—dark-colored in black varieties and orange or red in albino varieties; male guppies have no gravid spot.
II. Color and Fins
Vibrancy of Body Color
Male guppies have bright body colors, with richly colored tail fins and dorsal fins; female guppies have lighter body colors, though some artificially bred female varieties may be more vibrant than males.
Shape of Pelvic Fins
Male guppies have thin, needle-like pelvic fins, while female guppies have fan-shaped or triangular pelvic fins.
III. Distinguishing Juvenile Guppies (Subadults)
Coloring Sequence
Juvenile guppies can be distinguished at around 40 days old: those that develop color first and have shiny tails are mostly males, while those that haven’t shown color are mostly females.
Anal Fin Shape
During the subadult stage, male guppies have a thin, pointed anal fin, while female guppies have a rounded, arc-shaped anal fin.
Note: Artificially bred varieties may have variations (e.g., females with bright colors or pelvic fins similar to males). It is recommended to make a comprehensive judgment by combining multiple characteristics.