Also he looks quit big... id give him either rat weanling to a smaller small rat.... Aswell take ur cage and put Black paper or w.e color around 3 sides, only exposing front(more secure) bcz if its in a bio class it will be stressfull for a bit so he will decline meals, I think your best bet is to warm the rat/mouse before you leave and drop it in (warmside) if he doesnt strike.. by morning its gone