Refers to fish that is fresh, often in contrast to frozen or processed fish. Common in markets, restaurants, and news reports.
This shop stocks fresh fish from the harbor every morning.
This shop gets fresh fish from the market every morning.
鮮魚コーナーで、今日のおすすめを聞いた。
I asked for today's recommendation at the fresh fish counter.
That shop specializes in dealing in fresh fish.
The chef quickly fillets the fresh fish.
活魚 refers to fish kept alive (e.g. in a tank), whereas 鮮魚 just means fresh, not necessarily still living.
冷凍魚 is fish that has been frozen, the standard contrast to 鮮魚 (fresh, unfrozen fish) in markets and shops.
fish shop; fishmonger; fresh fish retailer
Compound of 鮮 (fresh, vivid) and 魚 (fish). The reading is on'yomi (せん + ぎょ).