I just got some new additions to my tank last thursday (its been 4 days now) and when I feed my fish (combination of Formula 1, Formula 2, and Reef Flakes) Every fish in my tank eats but my New Powder Blue Tang. I even have tried green seaweed sheets. All of my other fish go for it but the new powder blue tang? This Powder Blue tang will try to eat or pick on the live rocks occasionally but it will not eat food when I put it in the tank? He is looking thin (I can see his spinal bone). He swims around the tank and seems to be kind of agressive to my powder brown tang. The powder brown tang eats, but he stays hiding in a cave, when he tries to come out the powder blue tang chases him back in. Any ideas? Thanks I do 40 gallon water changes every 2 weeks, and everything else in the tank seems to be normal and the other fish are very happy.