Tangs in general seem to eat in the wild, all day long,,,,,so it's a good idea to keep them well fed and happy in a tank,,
Like Casey said , Nori is a good thing to use, and you will be able to leave it on a clip on the inside of the tank , for it to feed a good part of the day.
Tangs and Angels, have a short digestive tract. Food in, waste out,,,in short order,,,hence the grazing they do all day on the reef.
Good foods, with a lot of it being comprised of greens/algae matter will help keep your tang in good health.
Check out our archives here, do a search on "tangs" and i bet you will find a lot of info pertaining to tangs,and their care,,,,,:thumbup: And if you don't find what you are looking for, feel free to ask away here!