The technical name is either copopods, amphipods,they are tiny crustations. it is a great thing. It shows that your water is healthy and the system has stabled out.! Congrads. There are some types of fish that eat these on a regular basis (hawkfish or mandarins) but it usually takes a large amount of these creatures or the fish with slowly starve to death. Usually these crustations come off of your live rock or sand. Hey good job!:jumping: