When you want to breed Bettas then there are some steps that you must follow.
Conditioning for spawning process
You should feed the fish on a variety of foods. You should also condition a pair of fish for about a week.
Setting up the spawning tank
A ten gallon tank is about the best bet with three inches of water. You will need a 50w heater that is submersible as you do not want to cook the fish! Also a sponge filter and a lot of plants. You need a sealed lid for the top of the tank as the betta fry need air and water temperatures to be about the same.
You should set the heater to 80 degrees no less and no more. Start this off about a week before the spawn is due so the water is balanced and stable as the temperature is very important here. Get a container like a glass lantern chimney and put the female in that so the male can not get at her but can see her. Put this near the spawn site.
Time to Introducing the Pair to the Spawning Tank
You should then put the male into a cup of water and let him float around in the spawning tank for around 30 minutes. After 15 minutes take out half of his water and replace it with the water from the tank. After the 30 minutes put the male into the tank. The same with the female but make sure that her container is closed so that the male can not tip it over because he will get excited. When her half hour has gone then put her into the glass enclosure where she should stay until she is released for the spawning process.
When to Release the Female Betta
Do not release the female too early that this can cause damage. You will see a sign when the female is ready to spawn as she will not be scared of the male and will even try to swim with him. The females stomach will be quite big and look as though she has swallowed a marble. Also she will show vertical bars on the body when she is ready to spawn. Lastly she will clamp her fins and swim her body slanted in a forward motion and will do a wiggling dance to let the male know she is ready.