I have five clutches hatched, 18 or so babies. I do not crowd them, but I keep 4-5 together per tank, and only one has lost part of a tail so far, and I don't think that was nipping. I think he got the tail caught on the cave when he was only a day or so old. But like I said, they are fed 2-3 times a day all they can eat crix and salad.