yellow tang feeding

[Godfry]

I have had a yellow tang for about 6 months now and he seem pale in color and his fins don't seem to be growing properly. Im wondering if I could or should be feeding him something different. Ive always fed my fish frozen brine and Mysis shrimp, all my other fish seem to thrive on this but not the tang. Any suggestions? (my other fish are 2 clowns, Dragon Gobey and blue stipe gobey)