Platies are livebearing tropical fish that belong to the same family as guppies and swordtails. Distinct differences exist between the sexes in terms of color, size, body shape and fin shape.
Color Intensity
Male and female platies tend to share patterns; that is, the same colors are found in the same locations on both sexes. The males of some varieties, such as red platies frequently have more intensity to their body and fin color than do females of the same variety.
Body Size
Female platies are somewhat larger than male platies. Female platies will grow to as long as 2 inches, while males grow only to 1.5 inches long.
Body Shape
Female platies have a rounder, heavier body than male platies. Females carrying young, known as gravid females, have a large bulge in their midbody area. This area, the gravid spot, may have a different color from the female's normal body color.
Fin Shape
The shape of the anal fin differs between the sexes. Female platies have a rounded anal fin. Male platies have a long, thin anal fin. This fin, called a gonopodium, is used to inseminate the female.
