Something to consider: please stop buying wild caught fish. At least then, you won't be hurting wild populations when yours keep dying. Hawaii's wild yellow tang populations in collected areas are 73% lower than those in protected areas. The state now officially calls the aquarium take "unsustainable". Please only buy captive bred fish!
I'm sorry to say but if you do acquire a yellow tang the chances that it will die after a few days are incredibly high, for now they are just not the kind of fish that can survive outside of the reefs. Sorry if that's a bit harsh but buying a captive bred fish will be much more rewarding as it is well adapted to life in a tank and will last much longer and keep all of its beauty in tact. Thank you for reading!