i have a reticulated stingray who who does not want to eat anything but ghost shrimp.i am having trouble getting ghost shrimp because the pet stores in my area do not carry them.i have tried feeding him frozen grass shrimp,red wiggelers,meal worms,andcut shrimp.he was imported febuary fist and has a diamiter of 5 inches,if anybody has any ideas it would be great help. thanks