i have one that bites all the time. but i took one of its little chews once and beated over the head. it doesnt bite to much anymore. hehe... i got a little wheel and it can fit three and four hamsters in at a time. its fun to watch when two are going on way and one another way. the one just gets going around the wheel alright. just not the way he would wish to 😈 😆 😇