Awesome! Thank you!! I had no idea that any fish vocalize until I tried to find an answer searching online. I find it all to be AMAZING! Thus far it has only been that one, at least that I've seen.
It being a male, it definitely makes sense that it's a dominance thing. The other two larger angels are also male. One just recently lost it's mate. He had been pretty docile since, but not anymore. I guess maybe his mourning period is over and now and he wants his top spot back.
I am going to rehome at least the largest male.
I have three small ones in the tank also, hoping at least a couple are female. They are still too young to tell right now. They're growing well, have more than doubled their size in the 4-5 months I've had them. Two of them are already very testy with each other, and they both hassle the other small one. For the most part, two of the big ones tend to ignore the small ones. The male that lost his mate could care less about the small ones.
It would be just my luck to end up having all males!!