I got a larger female to put in with the male rat today. He's still too young to breed I think so it should be okay. I also used a wire hanger and customized the water bottles to let them hang over the edge outside. Will they be able to chew through that? And the bedding is cedar I believe...we use it for our ferrets. I also got a new screen lid for the females. I feed them these little lab blocks. Thanks everyone!