Oh I was talking about a yellow tang in that size. I know a few instances of people who’ve kept them for years in that size tank at least a long version and it’s the minimum not the maximum and often recommended by multiple sites as being the minimum but it does vary. The Achilles was something someone asked about in the 125. I did try searching for the thread.Fyi there are literally dozens of identically titled threads asking the exact same where it has been discussed and fought about, if you are looking for more info.
What is the basis for Your opinion of 50g minimum? What specific Tang do you Think that is suitable for living a lifetime in? Is this based on experience keeping tangs? Have you ever owned an Achilles?