No.33 Asian Sheepshead Wrasse

A saltwater fish belonging to the wrasse family of the order Perchidae, it is found in coastal waters from Hokkaido to Kyushu. They are female when they are small and change sex to male when they get big, and they are said to compare their body size in territorial disputes.

This specimen was CT scanned at the request of NHK Enterprises, Inc. as part of NHK E-television's “Gyogyotto Sakana★Star” project.
The “Giggling Sakana★Star” program HP: https://www.nhk.jp/p/ts/P58QMGP4K1/

Although outward appearances indicate that males have a fuller hump and jaw, CT scans showed that the skeletons of males and females were almost identical.

It is believed that it was difficult to change the skeleton during sex change, and that it was easier to develop the hump and jaw by accumulating fat and protein.