My puppy has a loose, discolored fang but isn't in pain. What to do?

Thanks for visiting Petco Pet Education Center, formerly Petcoach. I do see a baby tooth there (the really pointy sharp tooth) and that is likely the tooth you are saying is really loose. Usually pets lose their baby teeth by the age of 6 months, so Vader is a bit of a late bloomer. I would recommend having your vet take a look at the tooth in person to see if it can be manipulated to come out. It may just come out on its own, but again, usually by this age the baby teeth are already gone. No need to worry too much however. If it does not come out on its own, then it can always be extracted at a later date. It is best to extract them to avoid overcrowding of the teeth and advanced dental disease. I would recommend brushing Vaders teeth often (3 times a week) to help remove foodstuffs that might get stuck there. Otherwise, plan on seeing your vet soon for further care if it doesn't happen to fall out soon.
Best wishes with Vader and good luck with his stubborn baby tooth. Take care.