Join Date: Oct 2010
Location: Victoria, Australia
All of your bettas should be kept separately, including the females. If you continue as you are doing, you run the risk of one or more fish being badly injured (as you've already seen) or even killed. These fish are solitary by nature and should not be kept together except for breeding.
Breeding bettas is not something to be taken lightly. Conditioning is needed to ensure that both fish are in peak physical condition, and it's not uncommon for one or both fish to die during or after the breeding process. For her own safety, the female must be removed from the tank as soon as they have finished spawning as the male will become very hostile towards her and will attack her should she approach the nest.
Then there's the raising of the fry. Unlike livebearers and other species of fish, betta fry will only accept live foods. Without them, most if not all the fry will starve to death in the first few days. Then you need to start thinking about grow-out tanks and jarring, and the daily or near daily water changes that will be required for the next few months.
The whole process is a huge undertaking for both humans and fish.