My personal opinion is that any animal who is not destined to be bred from should be fixed - far too many unwanted kittens and puppies in the world and no matter how careful you are, accidents can happen! And I think your pup is still young enough for the op to have a positive effect on his behaviour - I was once told by a vet that past two is too old and the bad habits are ingrained and can only be trained out. Of course, fixing doesn't replace training - still needs a firm hand by the sounds of him! Cute pup though!