* Body shape: Male Siamese fighting fish have a longer and more slender body shape than females. Their fins are also longer and more elaborate.
* Color: Male Siamese fighting fish are typically more brightly colored than females. They may have red, blue, or green bodies with iridescent scales. Females are usually duller in color and may have a yellow or brown body.
* Behavior: Male Siamese fighting fish are more aggressive than females. They will often flare their fins and display their colors in an attempt to intimidate other males. Females are more peaceful and will usually only fight if they are threatened.
If you are still unsure whether a Siamese fighting fish is male or female, you can gently squeeze its belly. If the fish releases eggs, it is a female. If the fish does not release eggs, it is a male.