It is recommended to stock at least 3-6 platies together in a tank while maintaining a ratio of one male for every two female platyfish. You’ll therefore need to differentiate between male and female platyfish to accomplish this.

Here’s how to differentiate and tell the gender of platyfish:

Adult female platies are bigger, measuring about 2 inches compared to males which grow up to 1.5 inches long. Also, the anal fin (gonopodium) in males is more prominent and long, while that of female platyfish is simply fan-shaped.

Male platyfishFemale platyfish
Grow up to 1.5 inches long.Grow up to 2 inches long.
Have a longer, pointy anal fin.Have a smaller, fan-shaped anal fin.
Male platies have leaner, more streamlined bodies.Females have bigger, rounder bodies.
Male platies have colorful, showy scales.Females are less colorful than males.
Male platies are coercive towards females.Female platies are generally peaceful.
Difference between male and female platys
Difference Between Male and Female Platys Pictures

Color differences

Research has found differences in how male and female fish in the Poeciliidae family evolve differently and may exhibit varying intensities of color. (Source – Michael Tobler and Zach Culumber).

Generally, male platies exhibit more flashy, colorful scales than females, which helps identify them, especially during mating periods. The showy colors of males are meant to attract females for mating.

However, while color is a major distinguishing factor between male and female platies (fish in the Poeciliidae family), it is mainly an evolutionary adaptation to increase mating success.

Some types of platies may not show major differences between genders colorwise because the males adopt a coercive approach to increase mating success.

Anal fin

The anal fin is a reproductive organ in platyfish and one of the standout physical features you can rely on for distinguishing between male and female fish. 

Also called the gonopodium, the anal fin is positioned close to the anus, on the rear of the pelvic fin, and aids the platy in breeding with other fish.

Female platies have a broad, fan-shaped anal fin that almost resembles the pelvic fin while male platies have a pointy, much narrower anal fin.

Male vs female platy illustration

Body shape

Apart from being bigger, female platies have a more rounded and heavier body than males. You’ll notice pregnant platies having a bulging belly with more dark marks all over the body than you’d see in males.

Male platies have a more slender, thinner, slimmer, and compact body. They also have slightly sharper heads with a little caved-in forehead. 

The rounder and fuller body in females provides additional belly space for storing food and carrying pregnancies as livebearers.

The pregnant female platy, or the gravid female, has a belly that is slightly swollen, with an alternate shading of its center, unlike the rest of its body.

These characteristics can also make female platies appear visibly bigger.

The difference in body size

Size male vs female platies

Female platies have a slightly larger body size, usually 2 inches long, while males grow up to 1.5 inches long.

The sexual dimorphism between males and females becomes more evident when the fish mature to the age of reproduction. You may not tell the gender difference between them until later in development.

Gravid spot

You can quickly identify a female platyfish due to its gravid spot due to the uterus pressing against the skin. The gravid spot is available in the mid-body area of female platies but is absent in male platyfish.

The gravid spot is darker, unlike the rest of a female platy’s body. The spot becomes more prominent and visible as the pregnancy progresses.

How to tell if red wagtail platy is male or female

By physical examination, you can tell if the red wagtail platy is male or female. While the female red wagtail platy has a fan-shaped anal fin, the male red wagtail platy has a pointy, long, and flat anal fin.

When can you tell the gender of a platy?

Gender differences are visible when platies are between 5 and 6 months old. Platies younger than five months do not possess significant distinct physical characteristics, making it difficult to identify the gender.

Some male platies may suffer considerable maturity delays. As a consequence, the occurrence of male-specific physical characteristics will appear later, between six to eight months of age.


The main differences between male and female platyfish are the size and the shape of the anal fin. Female platies are visibly bigger (2 inches) than males (1.5 inches). The anal fin in male platies is pointy, longer, and flat, while in female platies, it is smaller and fan-shaped.

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