I currently have a 7" orbi ray and just got my 5" motoro ray today. I have been feeding the orbi red wigglers and frozen blood worms. The motoro I purchased was previously eating black worms. Our only local petstore does not carry black worms, nor do they even know what they are. The problem with the blood worm cubes is that they don't all like to sink to the bottom and most get eaten by the other little fish I have before they can sink. So heres my question....I have looked up places online where I can purchase live black worms. What I was looking at was I believe 1 pounds or 4000 worms. About how long do you think an order this size will last my 2 rays? Will they consume that many before the worms perish? And does anyone know approx. the amount (in comparison) how many black worms to 1 blood worm cube? Sorry, I know this is a lot of questions but i'm trying to weigh out my options and have no experience with black worms. Thank you for any help