mating chromis?

[niloc16]

curious if anyone has seen or had chromis mate in their tanks. for the past 2 nights i have had the 2 largest chromis of the school do a strange jitter dance next to each other at the bottom middle of the tank and then they scurry off to find a hole in the rocks. the holes have not been their regular sleeping spots though. while they are doing this the other chromis create somewhat of a circle around the two, i dont know if it is to protect them or to observe what is going on. if you guys want i'll try and get some pictures.