I have 2 yellowtail damsels (really dark blue kind no the bright blue). the "big one" is about 3 inches, and the "small one" is about 1.5 inches. They both stay on opposite sides of the tank. And the "big one" stays in it's cave, and only comes out to eat and chase the other one. It protects it's cave pretty good. Now today the small one was in the cave with the big one and were swimming around in a little ball, swimming upside down, and rubbing there under bellies on the roof of the cave. Now on the cave walls there's thousands of these tiny black and white things, are these eggs? I have included a picture I just took, but It's the best I could do. What should I