I agree with BadRattitude, but if your babies are six weeks already and you are just separating them, I wouldn't panic. While he may be the exception, the guy who I got my first two rats from (he had an accidental litter out of a Petco rat) didn't separate the babies until 6 weeks and a few days of age. He didn't end up with a single pregnant rat in the bunch, including the mother, and some of those boys were BIG. I wouldn't recommend what he did or anything, but it's just FYI.
