noun
threadfin butterflyfish
A species of butterflyfish (Chaetodon auriga) with a distinctive thread-like extension on the dorsal fin.
トゲチョウチョウウオはインド太平洋に広く分布している。
The threadfin butterflyfish is widely distributed in the Indo-Pacific.
ダイビング中にトゲチョウチョウウオの群れを見た。
I saw a school of threadfin butterflyfish while diving.
Compound of 棘 (toge, 'thorn') + 蝶々魚 (chōchōuo, 'butterflyfish'), referring to the thread-like dorsal fin extension.