snowflake help

[reefnut]

had him for about 3-4months.he is about a foot long.for the first month i fed him aqua yums frozen krill on a stck.he never really got excited about food and woul only eat about 4-5 a week then i tried feeding him frozen shrimp at first he loved them but now he refuses to eat them.i went back to the frozen krill and he seem not to even notice them anymore.he hasnt grown at all in the time that ive had him and i think he is malnourished.the only thing i can seem to get him to eat now are live ghost shrimp and he stiilm only eats two small ones every opther day.what can i do to spark his appetite and get him eating more?