If you're buying a female or a plakat?!?!!!?? I saw many "female" betta's tonight at PetSmart but they looked like plakats to me. Now I'm far from an expert but I'm also not ready to buy into what PS says it is!! They had a CT in a VT labelled cup!
Females are usually more rounded in bodyshape, have shorter anal and ventral fins, and you will see their ovaries which look like big whitish or pale areas on their sides which are full of eggies, and little white dots on the bottoms of their bellies called oviposters. Females tend to flare straight ahead and have much smaller beards. They may also have vertical bars or stress stripes.
Males are more torpedo shaped and streamlined, have longer fins all-round, and have smaller bellies. They also might have oviposters, but it's usually only seen in young males. Males tend to flare sideways, and have much larger beards.
Hope this helps a little!
/ Quill (Brown Tabby and White Pancake Monster)[/FONT]