Why do you wanna breed? Is it to improve the quality? Or to make extra money? When breeding, you need lots of space and time and not every pair can breed. If you put a few in breeding box, there are chances where the females will feel stressed.... some may cannibalize each other's pups.... the best is only pairing them up when you want to breed. A hamster that is breeding need to rest, if you keep breeding non-stop, you shorten the lifespan by half.