I know mine is/was. I got it at about 2.5" and 4.5 years later she's about 8". The first year it seemed like a very tiny amount of growth. It wasn't until year 3 that she seemed to pick up the pace. But definitely not a fast grower like a vlamingi or rabbit at all!Is your Naso a slow-grower? Mine seems to be-- I thought he'd really take off (like my Rabbitfish has).