Zanclus Canescens-Moorish Idol
A very tough fish to keep and should only be tried by a very expert hobbyist and even then it's probably best if left in the ocean. Most come in very thin and even if they're eating don't make it.

If you looking to get one make sure the body looks fat and around the face and mouth looks in good shape, not wounds by the mouth that would cause it not to be able to eat. They need to be place in large tanks with very non-aggressive fish otherwise they can be bullied very easily. Best left in the ocean.