Myths about sexing bettas
When you have a tank full of juvenile bettas, sexing them can be quite tricky as a new breeder. I thought it might be helpful to other breeders to share some of the things I have learned about this tedious task. There are 2 main myths I would like to clear up.
If the betta fish has what appears to be an egg spot, the fish is female.
Fact: Although this can sometimes be true, there are exceptions.
I have seen young bettas that have what appear to be egg spots at a few months of age that turn out to be males. The "egg spot" mysteriously disappears as the fish grows longer fins. Things are not always as they appear.
This picture is a good example of a young male that seems to show an egg spot.
This is the same fish about a month later.
If the betta fish shows vertical bars, the fish is female.
Fact: Immature male bettas will often show vertical bars while in a group of bettas. Vertical stripes is how bettas show submission, and even an adult
male may show vertical stripes. When a male betta shows these stripes, it seems to communicate that he is submissive to the other fish. Perhaps
he is scared, stressed or wants to avoid a fight.
Here is a juvenile betta showing vertical bars that later developed into a male.
The only sure way to tell apart females from male bettas is to hold the fish up to a very bright light and look for ovaries. The body shape is often shorter and curvier on female bettas, but well fed juvenile fish can all look curvy. The anal fin and ventral fins of male bettas is usually more pointed
and longer. Female plakats may appear to be male if you go by fin shape. Unless you can see ovaries when held up to the light, the fish might not be female.