Aquarium compatibility

I’ve had Siamese Fighting Fish for a while. I’ve bred them before, with great success, but I’ve stopped caring. I’m tired of the intricacies of their whole breeding regiment. I have one male and two females. I’m thinking of doing something simple, like adding fantail guppies to the tank, and breeding them, as guppies can breed in toilet water if they want to. Though, something tells me that the Bettas would go after them unmercifully.

Anyone know for sure?