noun
saltwater fish; marine fish
Refers to fish that live in the sea, as opposed to freshwater fish (淡水魚). Common in everyday contexts such as cooking, aquariums, and biology.
この水族館には珍しい海水魚がたくさんいます。
This aquarium has many rare saltwater fish.
海水魚は淡水魚より飼育が難しいと言われている。
It is said that saltwater fish are harder to keep than freshwater fish.