Well, this post answered my last question. You need a larger tank to fit the tang and angel fish in.
You should feed nori about 3 times a week. They will also eat meaty food, like mysis. If he won't eat, try soaking food in garlic guard (no scientific proof on getting them to eat) but it has been proven to strengthen their immune systems. From my experience, when I add the garlic, the fish go into a feeding frenzy. I would also soak in Zoe and Selcon.