How to beat the King of the tank

Hi Everyone. I was wondering about how to thwart the king of the tank killing new tank additions. My situation - I have a Humu trigger that is boss hogg! He was the last fish added and is very cordial to his tank mates but try adding something new - and it is on til the new guy is no more! I have tried lights off, feed well before addition, hang in tank in breeder assembly a couple days before adding, rearrange rock-work (which i hate doing), nothing works. Does anyone think pulling him out, adding new fish, then put him back in after a certain time, say 4-5 hours will help or will he remember, which is an interesting question for a separate thread - Do fish have memories? Removing him from the tank permanently is not an option as i want to keep him. I want to add 1 more fish and i am good. Thoughts or Ideas?



72G bowfront reef, 25 g sump, reef octopus 6520B, RO/DI, 324W T5 - Humu, Koran, Hippo tang, Yellow tang, Maroon clown, foxface, gold banded shrimp ricordeas, various mushrooms, GSP, frogspawn.