I feed mine a bunch of different things. Some of the things I feed him include:
1.) Frozen mysis shrimp- I highly recommend this as a food source. My coral beauty really like them.
2.) Seaweed sheets with a veggie clip- My Coral Beauty shares this with my tang
3.) Algae flakes- I have some spirulina enriched algae flakes which I feed mine as well.
4.) Chopped Fresh Seafood- I chop up some squid, clam, shrimp and put that in the tank. He will eat that as well.
Mine will eat the regular flakes but prefers the other food more. I have never had much luck with any of my fish eating the pellets.
As an aside, I have heard that it is best to alternate foods and not feed them the same thing over and over again. Sometimes I feed them flakes, sometimes seaweed, sometimes frozen, sometimes fresh.