Como saber o sexo do peixe?

How to know the sex of the fish?


Finding out whether the fish is female or male can be either an easy or extremely difficult task. This will depend on the species of fish, because some have physical characteristics indicating sex, while others have few signs.

To find out the sex of a fish, you must mainly observe the animal’s physical characteristics and behavior. Fish species are very diverse, so there is no single rule on how to know if the fish is male or female, this may depend on the particularities of the species. Additionally, you can consult an expert for more information.

It is common to hear that male fish of a certain species are territorial and quarrelsome. Therefore, it is best to avoid placing them together in the same aquarium, in which case knowing the sex of the fish is important to take proper care of the animals.

Check out how to identify the sex of the most common fish species in ornamental aquariums.


Betta are common and very popular among fish owners. To know whether this fish is male or female, one of the main differences is the size of the fins, the females’ fins are short, the males’ fins are long and exuberant.

Another important difference between Betta fish is the difference in colors, which tend to be stronger and more vibrant in males. They also have a wider body compared to females, as they are more elongated.


Differentiating the sex of a Giant Angelfish is not an easy task. When they are new fish it is almost impossible to distinguish. In adulthood, some discreet differences can be observed. In females, the head shape is usually slightly more rounded, and their belly is usually wider.


The Kinguio species is also one of those that presents subtle differences between the female and male fish. Females tend to be wider and rounder than males, and some may have protruding bellies when they begin to develop eggs.

In males, which tend to be more slender and elongated, the main characteristic is the appearance of so-called pearl organs, which are small dots that appear in the operculum region near the head.

Regardless of the species, it is easier to distinguish whether the fish is male or female when they reach sexual maturity, it is from this period that the differences become more visible.

Did you enjoy learning how to identify whether a fish is male or female? Tell us here! And if you have a fish, tell us here too!