A starfish can be offered meaty food about once or twice a week. The rest of the time the starfish can pick around the tank at natural growth. Careful feeding raw fish from the grocery store to aquarium animals. Stick with frozen fish meant for fish to eat...not what is meant for people to eat. There's more of a risk of the starfish getting sick...or anything else that eats it.
Most of the raw fish on the market as people food are meant to be cooked and therefore not really treated for pathenogens. Raw fish for fish to eat are treated for pathenogens mainly because it gets eaten raw. I won't eat sushi or any raw fish for that matter. I know what lives inside the flesh of fish...eeekkk...LOL. Gotta cook it.
Frozen squid, prawn, and silversides are readily available at any LFS.