the sites I read, seem to say min 40-50 gallon, but then again, Ive seen varied things on min tank requirements depending on the site.
That said we have one in our 44
what I cant find on some sites is the "swim room" like Tangs require, at least in some discussions, the Tank GALLONS isnt the only Factor for fish like Tangs they need horizontal distance to freely swim in, from what I think I understood anyway.
In reality, who are we humans to decide what a fish OUT of its normal enviroment should live in, bet if we ask the fish it will say PUT ME BACK LOL