I have a 1.5" going on 3 months. Small ones tend to adjust better because they have more of a mixed diet of algae, then other Beauties which tend to eat more strictly sponge. Try to feed him as much sponge based foods soaked in Selcon or Zoe&Zoecon(preferred). If you have a 'dirty' tank, bit of hair algae here, some cyano there, it will help. Also see if he'll eat macroalgae (chaeto, caulerpa). Other great foods include scallops, New Life spectrum pellets, PE Mysis, and fresh clam.