Same here.My young motoros have taken Massavore pellets almost from day one.They won't even sample any meaty foods that I drop in the tank.I feed my rays sinking carnivore pellets. All my rays have always chosen those pellets over any other. I also feed raw prawn and sol fish every other day. eBay is a good place to get pellets cheap
My rays have and always will get fed 95% prepared frozen meats. Fish food has a shelf life and is produced with wheat bases scraps from fish farms and easily pollutes aquariums. Even my largest of rays make messes while chewing up pellets.