Female Betta Warning!?

Question

Today when I was in walmart I discovered something that I felt needed to be addressed as a warning on here. Not all of their female bettas are actually females...some are short finned males. SO PLEASE PLEASE PLEASE if you are setting up a sorority betta aquarium make sure you are getting the females. They should be slightly smaller and not as aggressive (flaring) as the males. (ALthough there are exceptions). This really could be disasterous if they are put together

Answer 1

There is no such thing as a short finned males. The only true impostor of a male as a female betta would be a Plakat Betta and these types are never sold in petstores due to rarity.

The short finned males might be young males, or just young females. The flowing fins are male Veiltails. Whether jagged/tattered fins are male crown tails.

Female veiltails look like any other female.

Look between the front two fins, see a white dot? Clear indicator that is a female.

______________________________________...

Editted:

As said that short finned is a crudely termed PLAKAT Betta.

As said again, look for ovipostor to determine if female or male.

("'\(o.o)/"')

Answer 2

Often times juveniles are sold together.  Before maturing they are difficult to tell apart, so they may be clumped together as females.  The males will later develop some color and longer fins, although not necessarily the long flowing ones we're used to.  

This is for Betta spendens.  Other Betta species can be more difficult to s*x, and usually don't have the fancy finnage.