Im making my own food for the discus I have in the same tank as my 2 motoros. The recipe is really everything a stingray eats as far as raw shrimp, prawns, bloodworms etc. But I haven't heard of anyone feeding their stingrays beef heart and Im wondering 1) if its safe for them .. and 2) if they will like it. If not, does anyone have any other suggestions of a substitute to put in the discus food that will be safe & happy for my rays. Thanks!