Some people encounter the problem when they get a betta of is my betta a boy or a girl? Sometimes male plakats are mistaken for females and sold as such in petstores. I cant tell you how many posts ive seen on forums that ask the question “What gender is my betta” So I’m writing up this article to help people with that question come to a correct definitive answer.
Obvious Differences Between Males And Females
The biggest difference that will help you decide male or female is the way your betta flares. When a male flares he will have a large extra membrane appear forming a beard like presence around his whole chin. Females DO NOT have this membrane. Just because your female flares at other fish or even her own reflection it does not mean that she is actually a he. Some females are just naturally very aggressive.
Male vs. Female Body Type
Looking at the rest of the body there will be one other large difference between males and females, even in plakats. The males almost always (90% of the time) have much longer and fuller ventral fins then the females do.
Here is a male plakat, notice the long think ventrals, and you can even see his large gill membrane tucked in even when hes not flaring.
Here is a plakat female, notice the short thin ventrals, the lack of any kind of large gill membrane.
Both male and female bettas flare, both at their own sex and at the opposite sex when they can see them through their container. The fact that your betta flares is therefore no guarantee that it is male.
There are some subtle differences in the manner of flaring between male and female bettas though. Male bettas often (but not always) turn sideways onto an opponent and cross their ventral fins. Female bettas often, after a while, flare at male bettas in a submissive, head-down posture. They are unlikely to do this straight away, so patience is called for if you intend to use this as a component of sexing your betta.
It is a common misconception that the presence of an ovipositor (the white speck between a fishes ventral fins) is evidence that it is a female. Unfortunately, life is not that simple. Numerous males display the ovipositor, so much so that in IBC shows it is a disqualifying characteristic in a male.
So, if your betta has an ovipositor, it might be a female. But if it also has long fins it is probably a male. Even if it has short fins and an ovipositor it may be a plakat male.
Another common misconception is that only males build a bubble nest. This is not true. Females build bubble nests too. In fact many have been witnessed to create a bubble nest, drop a load of eggs, place the eggs in the nest and tend to them, before they are eventually eaten!