My mice have been very active during the nights, I can hear the male getting busy with the ladies!!

As for my rats, they sleep ALL day and then at night the male rat (a smaller medium rat) basically eats, drinks and sleeps again. Will he reach an age when breeding instincts awaken? I've got three large girls that are nice and bright eyed at nights and he just wants to sleep!!

Also, I had an extra male weaned rat that the breeder gave me during my last pick up. He is now about the size of a small rat and is doing great, very tame and loves to be handled since we've handled him daily. Would it be ok to place him with the large females? We've been keeping him alone in his own tub, but I'm assuming he gets lonely.

If later on I introduce him to the females as a male breeder, will they attack him?