The food would be clam, squid, fish flesh...even UNCOOKED table shrimp that you and I would eat. I used to thaw a shrimp out, take the shell off and just drop it to him. Spot fed just means making sure the anemone gets it and not all the other animals - shrimp and fish will readily steal your anemones meal.
However after years of feeding my carpet anemone once or so a week, I read that it is not necessary. Anemones get most of what they need from light, so feeding meat isn't the way to go. Anyone have any input on this as I'm not 100% sure.