I would try using a variety of other things like Formula 1, 2, other types of flakes, Seaweed Selects and other frozen fares because you really need to "wean" the Naso off the nori. I mean yes it is a good supplement and a tasty treat that tangs absolutely love, but a tangs diet consists of many other things in addition to just Nori. I personally feed my tangs, angels, etc. TetraMarine Flakes (w/ garlic/vitamins), Nori, Seaweed Selects, Frozen Brine/Bloodworms, Spirulina Tablets, and I'm in the process of making my own homemade food. I had a regular Naso about a year ago and the only thing it would eat was Romaine lettuce and Nori - needless to say, it was not providing enough nutrients to support the fish and he eventually became sick and died. Also, try soaking these foods in garlic/vitamins (Selcon, Zoe, Zoecon, etc.). They add to the nutritional value of food, act as an immune booster and sometimes entice picky fish into eating. Good Luck!