Even though you don't need to feed them, I do just for the fun of watching them eat. Like kingfisher62, I first throw some pellets in on the opposite side of the tank for the crabs and shrimp to fight over and then turn off the pumps and use a turkey baster to dribble food right onto them. Then I stand over them with a stick ready to beat back the crabs that lost the fight for the pellets. They get whatever I feed my fish that day from the frozen variety pack.