Yea, I was pretty surprised the first time those clowns attacked my hand. Without the background music, those two guys weren't really that tough after all but I think it is a good example of reality versus the Finding Nemo movie
Speaking of the movie though, at the very end, you might be able to see an example of what I was trying to explain about the horse-shoe shaped rock work. To be perfectly honest, I didn't (and still don't) have a choice for doing this in my tank because I have a centered overflow but the point is, unless my fish are out in the open in the middle of the tank, they can't see all of the way across. (FYI - this is also a common 'trick' for those with some of the more aggressive FW
fish as well)
Anyways, I apologize if I missed where you may already have said so but what kind of chromis do you have exactly? For the most part, I've almost always had four or more of the blue/green chromis in my tank and they've seemed to be some of the best schooling fish that actually school for what seems like a longer period of time than some other fish might and I admit that I am a bit surprised to hear that you are seeing one chasing the others....assuming that you have the blue/green variety. On the other hand though, some "chromis" are little more than damsels in disguise, which I found out when I bought 7 "blackmouth bicolor chromis" one time. Point being, sometimes the guideline that Kurt Nelson explained gets blurred by loosely used common names and depending on what type of chromis you have, it may turn out to be a good idea to trade some fish for others of a different species. However, if not, I still agree that often times, chasing can be mostly harmless so if you really do not want to part with your current fish, maybe you don't have to.
Just some ideas,