Some anemones don't need feeding. I think it's ccCapt that has had a long tentacled anemone for years and hasn't fed it. If you do feed, they will take meaty foods like krill, squid, mysis, etc. Same thing fish eat. You target feed them using a turkey baster. More important than feeding is lighting. Anemones need very strong light -- stronger than most corals. And they need very good water conditions and established tanks. So they are not appropriate animals for a newly set up tank. Usually the recommendation is that you shouldn't add an anemone to any tank that has been set up for less than a year.