How to differentiate between a male and female betta

The pictures below shows bettas belonging to Kevin Pelletier.

Note: I made a mistake of naming the dorsal fin as the caudal fin. Thanks to Ben who pointed out the mistake to me. The fin on top of the betta's body is called DORSAL FIN. The tail is also known as CAUDAL FIN.

Another mistake pointed out to me by Wal Anderson. Gill fins are actually PECTORAL FINS. I have also wrongly named VENTRAL FINS as pectoral fins.

A long finned male betta will have long fins......: ) But not the female....as you will see below.
1. The male will have much longer VENTRAL fins as compared to the female.

2. More aggresive, will flare at other bettas (male or female) and his own image. Females flare too but as aggresive.

 

The female can be differentiated by the body shape, fin length, colour and some special characteristics.
1. They usually have a bigger belly, bulging from eggs.

2. Fins are short, no matter whether they are long-finned type or short-finned.

3. Colour are usually not as bright and appears duller. But this is not always the case.

4. They have a ovipositor for laying eggs, which appears as a white spot under the belly.

5. Usually exhibit the horizontal stripes, even when they are not stressed.

6. Their pectoral fins are not as long as males. Usually short like the female above.

7. Vertical stripes appear when they see a male.