I know I took a big chance when I got mine because I got the yellow tang first and had him over two months before adding the Scopus tang, and the Scopus was a lot smaller than the yellow tang, but after a day or two of filling each other out, they have done great together
I know, I had been told to add a yellow tang last. Well I am not done adding fish, but an opportunity came up up so I took a chance. Went into quarantine first and then into the big tank in a peacemaker for 2 days and then in it went. Never saw any fighting, just skiddish for a couple days. Now they follow each other around. Just too funny.