Just wanted to throw some info in here. Everyone keep saying "I won't feed any saltwater items to rays" -- but you should probably clarify that to being in regard to rays that are strictly freshwater (S. American rays). D. sabina (Atlantic Stingrays) are growing in popularity and while they do live in freshwater, they are designed for saltwater and thus should be fed a mix of fresh and saltwater foods. I feed my female raw shrimp, feeder goldfish, and freeze-dried krill. Have tried earthworms, redworms, carnivore pellets, and various chopped up raw fish but she won't take any of them, even after starving for 2-3 days. Am working on coming up with some other ideas.
Mazuri also makes a shark/ray diet that comes in various forms. I purchased the powder form that becomes a gel when mixed with water, so when it gets here I plan to inject it into her favorite food (shrimp) to balance out her nutrition.