Ocean Fish
Saltwater Fish
noun
An ocean fish is simply an ocean fish. They also happen to be the most delicious kind of fish.
かいぎょ
うみざかな
This is a jukugo word, which usually means on'yomi readings from the kanji. If you know the readings of your kanji you'll know how to read this as well.
Some people also use the kun'yomi readings, but it's much less common, and generally considered colloquial.
さけは海魚ですか？それとも川魚ですか？
Is salmon a saltwater fish? Or is it a freshwater fish?
海中には、色とりどりの海魚がおよいでいました。
In the sea, there were a lot of colorful ocean fish swimming around.
水族館には沢山の種類の海魚がいますが、スタッフは僕達に一匹も食べてはいけませんと言いました。
There is a wide variety of saltwater fish at the aquarium, but the staff said we’re not allowed to eat any of them.