I have one red rose bubble tip which will be two years old in September and a second one will be one year old in October. I recently added four green bubble tips in the last two months.
I have fed the anemones razor clam sold by the Quinalt Tribe here in South Puget Sound in one pound packages which I thaw and then cut into approximately half inch size pieces which I put into a rubbermaid container and freeze. I cut off blocks which I thaw and feed once per week. The size of the bubble tip determines how much I feed and I get used to seeing how much each will take. The smaller the anemone the smaller the food.
You could feed small cut up pieces of razor clam and feed with a small wooden feeding stick, etc. My anemones love it and when you buy them whole you will get all the high nutrition intestines and fat not to mention the high protein flesh.
I did stop at a local fish market and bought three pounds of squid. I have small fresh scallops from the grocery store. The squid meat is not as firm as the razor clam and the same with the scallops although the anemones will eat them, it appears the razor clams are their favorite.
The squid smells to high heaven when I feed it.