I picked up three 3" grammodes about a week and a half ago and they are currently in my 8' tank. When I got them they were thin and looked hungry. My problem with them is that they don't come out from behind the rocks in the tank to eat. I've tried floating pellets, sinking pellets, and earth worms. Should I continue to feed what i have, try a new option, or just wait and see if they become less shy.