Aaaaah I’ve been meaning to make a sexing bettas guide! I’m glad you asked.
First: You have to look at several things and join all those observations to determine if they are male or female. You can’t just say “I see an ovipositor it’s a female.” and call it a day. It could absolutely be a young male or a bloated male!
So the things to look for are:
And now some things that aren’t indicators of gender! I see this a LOT online and in real life and none of these are actually true.
- Color. Females come in every single color that males do. They can be JUST as colorful! Wild Betta splendens (and other wilds) can indeed be sexed this way. But NOT the bettas you see in the pet store.
- Bubble nesting. Females can and will build entire bubble nests. This means nothing!
- Aggression. Sometimes, females are JUST as aggressive as males. And sometimes they’re even MORE so.