Just buy some ghost shrimp tomorrow. She will take to them. Once you get her eating good then try to convert her over. Buy about a dozen of them and ask for some smaller ones. Then put all 12 in the tank and watch. Black worms are an absolute mess to use and I would only advise if she doesn't eat the ghost shrimp. As far as a good staple food, I feed mainly shrimp and scallops. I throw some raw fish in from time to time. I feed cooked shrimp just as much as raw shrimp. Everyone has their own opinions. My thought is if cooking food takes all the vitamins and minerals out then we would of died off a long time ago. Walmart sells a big bag of cooked salad shrimp that are about an inch long. The rays love them and I don't have to cut them up but my rays are larger.
.. truly amazing. i can just sit here all night watching her and even more so now knowing shes eating.