most crays are opportunistic scavengers. although all mine love snails, especially my larger species. i also collect fallen leaves in late winter, let them dry completely over the winter, then soak them in water for a week. after that i drop a couple into every tank and watch the fun. snails, shrimp, and crays go nuts for these. also there is no cost to collecting these yourself, just be sure you use oak or maple leaves as these are not poisonous.