Yeah it's a bit outdated as most 125's and 6 feet long- i've seen plenty of PBT in tank sizes as the only tang in the tank but normally as the only tang and does well, of course depends on the tangs temperament and healthyness but you won't always have the same experience. just put it there as i thought it said 6ft and that's a minimum for this fish.That thread had a lot of wrong info.
Ex. a standard 125g is a 6 footer not 5
And I disagree about 125g being sufficient for a PBT.