noun
aquarium fish; ornamental fish
Refers to fish kept primarily for display and visual enjoyment, such as tropical fish, goldfish, or koi in a tank or pond.
熱帯魚は人気のある観賞魚です。
Tropical fish are popular ornamental fish.
彼は自宅で様々な観賞魚を飼育している。
He keeps various ornamental fish at home.
Compound of 観賞 (kanshō, 'appreciation, viewing') + 魚 (gyo, 'fish'). The irregular form 鑑賞魚 uses 鑑賞 (kanshō, 'appreciation' with a nuance of critical evaluation), which is considered nonstandard for this word.