:welcome: HP and have fun.
Fanning is needed by Males, in order to keep the water circulation in the cave, usually for the eggs in side. As you can imagine, the cave is closed at one end and as there usually is no water flow in this cave, the male has to fan and do the job of circulating the water. Sometimes males do this to pratcise or territorial displays as well, however highly likely scenario is that there could be eggs present. How big is your tank and how many in the colony ? post a pic. cheers jk :thumbup: