noun
scorpionfish (general)
Broad term for scorpionfish, often used in fishing and culinary contexts. In everyday use, カサゴ typically refers to the marbled rockfish (sense 2).
カサゴは磯釣りの定番の魚だ。
Scorpionfish are a staple of rock fishing.
noun
marbled rockfish; Sebastiscus marmoratus
The specific species most commonly called カサゴ in Japan. A small, bottom-dwelling rockfish with venomous spines, popular in angling and cuisine.
釣ったカサゴを味噌汁に入れた。
I put the marbled rockfish I caught into miso soup.
メバル is another common rockfish, often compared to カサゴ in fishing; メバル has larger eyes and a different body shape.
The name カサゴ likely derives from 笠 (kasa, 'conical hat') + 子 (ko, diminutive suffix), referring to the fish's broad, hat-like head shape. The exact origin is uncertain.