none,
IMO, are suited for a 4' tank. sorry to be the bearer of bad news, but tangs swim for miles and miles in the wild while cleaning the reefs of algae. they all really need a 6' tank or longer. while a 6' tank only adds 2' ....
i did a little test when i got 2 tangs with Marine Head and Lateral Line Erosion. i got a Sohol and Chevron tangs from a local friend that had them in a 4' 120g reef (with minimal rock). they were both so bad off that you could not really tell what kind of fish they were. i got them home and put them both in my 8'
frag tank ... withing a couple of weeks they were both healing. the Chevron healed within 6 months and was moved into my display tank. when the Sohol was alone in the 8' tank ... his healing REALLY took off. he was 95% back to his former glory when i sold him to a friend (who knew of the disease). i truely believe that both tangs being in a 4' tank was the reason for the MHLLE disease in both fish.
i understand that you would only have 1 tang, but i still think that it would be asking for trouble in a 4' tank.
HTH
