It takes patience, creativity and dedication IMO. It may not work the very first time, but you have to keep trying and outsmart the fish. Yes, everyone nailed it down when it comes to ish, there are no similar characteristic.
I currently have 4 blacks and a Lei, the black are about 15" and the Lei is about 12-13".
It took me several tries of taking the aggressor out, separate him, changed the environment, leaving light on, leaving blue moonlight on and keep them well fed then try again in 1-2 weeks. But in the end, it can work and they all look gorgeous..
stan