I had (many years ago when advice came from LFS
, pre-Internet) a Hippo in a 55g. Did okay first couple years, got HLLE
after that and ended up dying. I've had Yellows (and a purple and even a Longnose Black), but always in large tanks and never had problems.
I spend a lot of time trying to convince people to really consider the tank sizes (not just for Tangs, for any fish) because almost every story you see with "my fish has a problem", involves a fish that is in a tank that is smaller than suggested. Rarely (almost never) do you see problems when those tank sizes are followed. That can not be coincidence with hundreds of cases just on this site. Too small environment causes stress. Stress is behind most fish ailments. IMO
, there are always those that get lucky and beat the odds for a while, but their luck will eventually run out.