
Masked Bannerfish (Heniochus monoceros) オニハタタテダイ – size 23cm
An adult Masked Bannerfish has the forward white bar through the body going to the spine on the dorsal fin. There are similar fish. Amami 2023

A younger Masked Bannerfish has a little different shape. Amami 2023

Head on view of the Masked Bannerfish so you can see the mask. Amami 2023

Four different butterflyfish here and a Morish Idol. The three that are similar are the Singular Bannerfish, Masked bannerfish and the Morish Idol (not even a Butterflyfish). See if you can tell the difference between them. Amami 2023

Masked Butterflyfish. Amami 2025