It depends on what kind of corals you are talking about. Most of the corals can just surivive with photosynthesis.
For my ricordeas i use to feed mysis shrimps. Euphyllia corals like frogspawns, hammer, etc can take meaty foods when their sweeper tentcles are out. A lot of LPS
will take meaty foods.
Lots of people feed with frozen cyclop-eeze, mysis, home made blend of sea food, phytoplankton.