Tangs need to be fed a couple of times a day. They are high energy fish with a matching metabolism. A mixture of flake, nori, and frozen would be good.

Remember that reef fish are accustomed to eating low nutrition food almost constantly. We, on the other hand, try to get them to eat an all you can eat buffet, once a day or every other day. Food goes through them very fast and they don't absorb a lot of it. Of course this means a lot of waste is produced that is high in nutrients. That is another issue, but the way to control nutrients is NOT to starve your fish.

They have a tendency to break out in Ich or velvet if they are stressed. Stress can include being under nourished.