Bettas (pronounced bet-tah, not bay-tah) are well known as fry hunters. If you do not want your guppys, platys or swordtails to overrun the tank, get a male betta to share the tank with them.
Bettas are carnivores in the wild and eat live food most of the time. They feed on small insects...
Don't worry about the fish, they will not have a problem sleeping. When they are ready to turn in for the night, once the lights are out, they will find a spot in the tank that has little or no current to disturb them. Do not turn off the pump at night, it should run continuously and is built...