Enemies? Angelfish, triggers, sometimes tangs, I've had sexy shrimp pick at my feather duster and cause it to throw it's crown. Lots of stuff will try and eat them, most reefsafe fish are fine with them. They are filter feeders so they will do best in a mature reef tank, should be fed live and dried phytoplankton. The smaller indo ones do better than the larger Hawaiians and come in nice bright colors.