i want a male, but i can't tell wich one is which. The pet store people always tell me the wrong information
the males have longer fins. the females generally are smaller and have short fins.
Males have bright colors and long flowing fins while females are dull colors and short fins. They usually have males in stores because they fight each other and females aren't that common in stores.
Many pet stores only sell male bettas because they are the pretty ones with the long fins; females have short fins almost like a normal fish.
This site explains and shows pics of each:
http://www.healthybetta.com/male- vs-fema ...
Normally they always have males, at pet stores, and they are much prettier with longer fins and are more nicely colored. Females are never really colored, and are a lot smaller with short fins.
Males have very long flowing fins at least over 1 "when it pet stores. A female has shorter fins. When looking at them, pick out one with long fins.
The male ones have long colorful tail fins and the females don't.