Precooked table shrimp really isn't a good choice to feed Clownfishes or anemones. Uncooked seafoods would be much better. Clownfish will usually take almost any prepared foods. Here's a partial listing of some other things that I feed Clownfish: frozen HUFA enriched mysid shrimp, HUFA enriched artemia (brine shrimp), nori, VibraGro/Saltwater Staple (crushed pellets), Ocean Nutrition flake, ProSalt Pro Green, Cyclopeeze.
A product called Selcon can be used to soak and enrich almost any food given to fishes.