oysters and scallops don't generally make good choices as they tend to be specialized filter feeders. It is difficult to adequately supply them with the appropriate particel size and the tend to starve. You could try feeding some of the small particle size coral foods.
_________________ Honda CRF150R
I have an oyster that came with some mushroom rock I bought. Actually the "rock" was the oyster with so many mushrooms covering it you couldn't tell.
It has been alive for almost 6 months. I don't have any idea what it is feeding on. I do a lot of water changes with Catalina water and feed just the basic frozen food.
Honestly, when I found it, I didn't expected it to live this long, but It keeps going.