People will call me the tang police, but I firmly, very firmly believe that the blues require a 6 foot tank. Mine is a big blob of fish, fat and big and he swims an awful lot. he also jams himself into the oddest spots, he just needs a bigger than average tank.
There is always debate about yellow tangs, some people have been keeping them in smaller tanks like 55g and 75g's, I wouldnt do that myself and I dont reccomend any tang other than a bristletooth species going into a 75g. People claim success but it's a long term thing and cant be shown to be doing well after only a few months or maybe a year. My blue tang has got to be in excess of 6 inches now and he was only about an inch long when I got him, if that. He grew very very fast too.
180g Reef - 60g Rimless Reef -90G FOWLR- 125g Malawi Cichlids- 40b REEF- 34g Fresh Planted-working on- 20L FOWLR- working on
I have a mix of many different saltwater fish amongst my tanks, but I love my Tangs most of all.