Have you taken him to any obedience classes? What type of exercise is he getting? It sounds like he might have an abundance of energy so maybe more exercise might help. Also when you see him coming tell him down, sit and do some training.
Hi and welcome to the forum! How old is your pup? Here are a few articles on teaching bite inhibition to a pup. Biting is a totally natural behavior for puppies because that is how they play with their littermates. They just need to learn to play differently with humans. It seems as if this stage will last forever but before you know it your pup will have moved on to bigger and better things....such as counter-surfing...hahahha! How about posting some pictures of your little piranha?