Introducing fish while there is an aggresive Tang

[Ruth]

I have a yellow tang in my 230g that is a real jerk and has killed one bannerfish that I tried to add. I did try the "Anthony egg crate method" but he just waited it out and attacked as soon as the fish was accessible. If you can catch the jerk (which I was not sure I could) you could try to relegate him to the sump while the new fish stakes out his territory and then add him back after a couple of weeks and then he would be the "newbie"