I hate when this happens.. I have three sibling rat females in together that I weaned about 1.5 weeks ago. Why is it that one seems to do so well, and the other two are lagging behind? Not that they're underweight, but still, it just seems like only one is the robust size and shape that I want all of them to be.. I feed them well enough for everyone to get some, and water is always available; there are two hidespots on the cage and usually, the two "underlings" take one, while big-girl takes the other.. I dislike seperating them because then big-girl will be alone. Any ideas??