Regarding the tank size, I have in a 90 gal w/ a radiata lion, blue throat trigger and a snowflake eel. FYI, I think it takes a very, very long time for them to get to a foot +. For example, Neptune's has a sailfin that has been in a tank their for 7+ years and his around 6 inches ... which is similar in size as my tang. Just the same, with my size tank and mix of fish, I have decided that my sailfin would be better off in another tank.
If I don't sell him soon, I have a LFS lined up to buy ... but trying to avoid this so he get's into a permanent home directly.