I was worried about him for the first couple of months that I had him. I tried seaweed select, nori, calerpa, formula two, spinich, lettuce he wouldn't eat any. I resorted to taking vitually all of my snails and hermits out so that he'd have any new algie growth for himself. He made it for the first couple of months off of just what he could pick off of the live rock.
I finally got the idea to take a small chip clip and attach a little seaweed select to it and place it in a nook by one of his favorite perches. He didn't eat it right away but it was gone a couple hours later. I continued this until one day I was feeding formula two and he swam up and grabbed a piece. That was it! Since then he eats straight out of the water column and he eats everything. Spirulina, formula two, angel formula, flakes, pellets, my home made meaty food. It's funny to watch him grab a chunk of formula and carry it back to a rock holding it in his mouth like a dog. He still grazes off of the rock and glass as well.
Long story but maybe you'll find something useful. Good luck!
Jim