Now the babies are old enough to be separated, at six weeks they are fully weaned; we don't want any more offspring thank you! Zak and Junior are going back to their old tank. But things can't settle down yet, because there was time for Zakky and Zaphy to have had mated again, before it was possible for us to split them up.
You see, if we had put Zak back in the first tank, before they had a chance to do this, than there would have been two problems. One: Zak would have got lonely, and two: he might not have accepted Junior as family; having been apart for a while.