What's the difference between river fish and sea fish?

Different living environment; Different tastes, etc.

The living environment is different: river fish live in fresh water and sea fish live in seawater.

The taste is different: sea fish tastes better than river fish. This is because the swimming range and swimming strength of marine fish are larger than those of river fish, which makes their muscles more elastic and delicious. On the other hand, river fish taste earthy because they grow in water with more humus.