Pseudobalister Flavimarginatus-Yellow Margin
This is a very rare fish that doesn't show up that often. You need to be careful if you do purchase one as small one get mixed up with Titan triggers, as they look very similar when small. If you see the start of a mustache, around the sides of the mouth, then it's a Titan triggers as Yellow Margin don't have mustaches. A fairly shy fish does better in FO or Fowlr tanks with aggressive fish, but not to aggressive.