[Aquattro]

So we always hear the rules about Tangs and tank size, because we know Tangs grow really big. Right?
So here's the thing. I've been doing this a long time, always keeping tangs, and not one of them has ever really grown bigger than the day I got it. Example, bought a 4 inch Yellow Tang. 8 years later, still 4 inches.

What's everyone else's experience with this? I did see a Naso that was about a foot long grown from a baby, but never my own tangs. And I feed a lot. Probably too much. I currently have 5 Tangs, none have grown at all.