ok i have a beautiful 5in panther grouper i bought him about 3 or 4 months ago when he was about 3 inchs. the problem is hes always been kinda scared of the silversides

whenever i drop them into tank he swims under the rocks and i have to get the fish out so my nitrates dont go up. on the other hand i can hand feed him anytime he will gladly take from my hand. now the big problem.. i dont want to hand feed this fish when hes all grown up! and my best friend is going to be taking care of him when i leave for 4 days in july shes scared of him(LOL) what the heck can i do? i dont want to be missing a finger!

anyone with experiance with these fish?