I've cut back on the amount of tilapia I feed. I tried w/c haddock and the rays seem to like it. For shrimp, I buy w/c shrimp now from the Gulf of Mexico.Poor quality also goes for shrimp from China. Any seafood or fish from China is absolutely garbage. I am feeding shrimp right now and it's says its from China. IMO it could come with a risk. Best diet for Rays would be home grown worms and pellets IMO!!!!