http://www.monsterfishkeepers.com/forums/threads/good-stimulus-for-young-rays.655115/Same issue I had Jim. Mine would blow under 1-.1.5 lb rocks looking for food. Started chipping the Eurobacing on my 340 bad enough the silicone has peeled off. Nothing but driftwood and substrate anymore. Will have to check into something similar to these Kongs. You have a pic?