sailfins are pretty mellow.
but the blue and yellow are not.
definitly add them at the same time like said and have plenty of holes in the rockwork.
i have 4 tangs in my 225 and they get along great.
i am not big on yellows they have the worst reputation for fighting ,funny because they are the cheapest.
my friend lost a $700 black tang to a $25 yellow a few months ago.
it was his own fault and he knew it.
he just added the black to the tank after the yellow was in there for months instead of removing the yellow to the sump for a couple weeks.
i love tangs and i will be adding a blond naso soon .its just a matter if more or less tricking them into playing nice.
when i added my 8 inch achilles to my tank my 5 inch purple swam out of the rock work and bit him on the side.the achilles just turned and looked at him once and that was it.
nature at its best.