I always figured the main way to tell a male from a female was its agressiveness, and its finnage.
I had a sorority tank of many bettas, all allegedly female (by the LFS), and as their numbers thinned for a various number of reasons, I was left with my 5 favorite.
I recently purchased a 28 gallon tank and started to move the members of the sorority and the plants in it over to this 28 gallon.
As time wore on, the agressiveness of one of the females really started to become more apparant. Its fins also grew substantially longer than the rest of the females. This female's fins look to be nearly as long as the majority of males.
I am aware that there are a number of female betta variants that have long fins, but this one's fins just grew and grew.
Are some bettas hermaphroditic like clown fish? I really woudl like to know, because it seems now that this last betta is by itself in its own tank, it has developed a monstrously different personality.
In being by itself it finds activities of its own such as more leaping in the tank, picking up pebbles and dropping them below. Inquisitive stares at me, and a desire to rearrange the decorations on its own.
Could it be, that all along, this betta is in fact a male, and was not properly removed by the breeder from the females?