Naso is a tough acclimation I have a beautiful male Naso Elegans (Blonde), that took 5 days to start eating--he had the pinched stomach and everything. He only had a yellow tang and a few small damsels to contend with, in a 120 gallon tank. In my opinion, the sailfin tang is probably the biggest problem to the acclimation--hes the nasty bugger. STOP! Don't kill any more--have you thought your tank may be at capacity? Side note, I hope you didn't move your Hippo into a 55 (that tang needs more room to swim). Also, I realize my Naso will need more room when he is a full-grown adult. As soon as he starts getting streamers, I will be looking to sell him to someone with about 240 gallons. He's happy as ever right now though.