Once that fish settles in, he wont be able to get enough of anything! Mine would not touch seaweed at first and now he rips it out of my hand. Also it is wise to vary the diet, one day new life spectrum then the next feed hikari frozen, next day Ocean nutrition flake(just an example), while keeping nori available at least every other day. Maybe look into some seclon or similar product. Tangs need a ton of nutrition, they eat constantly.