hey guys i was just wondering if any of you could help me identify what this fish is, i bought him about 6-7 months ago as a baby. the store i got it from is usually pretty knowledgeable about the stock they carry, but when i got this guy there was a new worker there and he had no idea what it was. i tried google for all tangs but have not been able to find anything. he changes color on a whim, can go from charcoal black to pale white in a split second. when he is pale in color his tail fin and the dorsal fin turn bright yellow. Any suggestions are appreciated.