Thanks guys for chiming in. I hope he does look good and big, but i dont want him to start getting skinny, Maybe move up to small rat pup, it seemed like that is why he/she rejected our offerings, wrong size, i will try and weigh him. His cage is blacked out, and he is in the lab, not the classroom so he really gets minimum kids in there, and when they are, he is usually invisible. I am going to try this weekend with a blow dryer Is the mouse being too cool making it invisible? I warm them in warm water in their bags for 10 min. He looks like he is hunting for the meal when its in with him, we give him privacy as in leave the lab for about an hour, but I worry about leaving him in there with a thawed mouse for too long, you know bacteria and everything, but overnight is ok? hmmm. What about his poop, he has only left urates since we got him, should we wait for him to defaecate before we feed/? I read that was not necessary.