if its only 3" just make sure you cut the meat up into small pieces. If the portions are too large it will either have a hard time downing it, or it will spit it up later when you arent looking
I feed my anemones 2-3x per week. Small raw seafood. usually soaked in Zoe for the nutrition boost
I just go to the seafood counter at my local grocery and pick up small amounts of thier stuff: clams, scallops, calamari, squid, whole octopus, raw shrimp, lobster, fish: like swordfish, tilapia, rainbow runner, whatever.
Just make sure you never give him cooked stuff. Its like rubber for them.
Good Luck! hopefully your lighting wont be a problem, just keep him fed and let him chose where he wants to be in the tank. Never try to put him where you want him, it stresses them out.
Jess