There are many different variations within the Ctenochaetus family, not to mention the differences between Juv, subadults, and adults, which makes it very hard to Id an individual.
It's a poor mans Gem tang! Lmfao
You are right as a juvenile supposedly these are a nice yellow and transition. The one I have is adult. It also has a pinkish hue with all the lights on.
Or a rich mans as I still go money (albeit not very much).