I remember reading others stress 6' tanks. I don't recall ever doing so myself, except for Tangs that are known to get very large, such as Hippo Tangs, which can become one of the largest adult sizes. I've usually recommended tank size for Tangs, by volumn, not length. Species of Tang also plays a large part in this. For instance, in my 75, I kept a Tang, but it was a Yellow Tang, which doesn't grow as large. In my 200 deep dimension, which is 4' long, I'm keeping 2 Tangs, a Purple and Lavender Tang, which also don't grow as large as many other. Even though the 200 is 4' long, it's also 3' deep. Lots of swimming room. Much different than the 75, which is 48X18.
It does seem like whenever people stress that Tangs are in too small of a tank, there's always those few, who come back and argue the fact. But again, it's not just about the adult size of the fish, it's about the fact that Tang's need lots of swimming room, even as juveniles.
As for a 6 Lined Wrasse, I have read where a lot of people having problems with them becoming bullies. I guess I've been fortunate to never experience that. Mine have never even bullied fish introduced after them.
