noun
fish swimming about in water
A somewhat literary or descriptive term for fish seen swimming freely in water, often evoking a peaceful natural scene.
池の遊魚を眺めながら、午後の時間を過ごした。
I spent the afternoon watching the fish swimming in the pond.
魚 is the common word for 'fish' as an animal or food. 遊魚 specifically refers to fish while they are swimming, often in a poetic or descriptive context.
Compound of 遊 (play, swim) and 魚 (fish). The exact historical derivation is uncertain, but the word is used in classical and literary Japanese to describe fish in motion.