Yeah, just watch those parameters . Doubling your bioload has got to cause something to happen. Your BB can't be enough to immediately handle that kind of increase, I'm down to two Chromis and my LFS
said to go up slowly to allow BB time to increase with the bioload, i absolutely sgree. I'm getting another Foxface soon and gonna add a new fish about every 3 weeks after.
That Emperor isn't gonna do well in a 120g. If you've ever seen a fully grown one, you'd understand. They get big and thick and even look out of place in a 180g, IMO
. Had one in a 300g years ago and that was probably enough space, but barely with all the other fish.