I have a Naso Tang myself, mine hid for the first day or so, but it eventually came out, maybe because the yellow tang and the clown chased him out, they all get along great. Mind you the yellow and the naso play tug o war every day when i put in the seaweed. Did you see it eat at the LFS before you bought it? I have heard of Naso's not eating for weeks then just giving up. If you can get them eating then your in the clear, it will eventually come out and play.I was lucky I had some bubble algea the naso gobbled up right away, and the the calurpa was next, and the algea on the LR and well, now it just eats the Nori, and picks at the rocks all day.