I house my Tokays in a 1.1 ratio. I have heard other people using a 1.5 breeding group but from my experience, once a female lays her eggs, she will become very protective of them, and I have seen one female bite another female's tail off and continue to attack the other female to protect her eggs. Unless you have a huge screen porch/greenhouse that they have plenty of room to establish their own territories I would always suggest a 1.1 ratio while breeding.