Whitefish or white fish is a fisheries term for several species of demersal fish with fins, particularly Atlantic cod, whiting, haddock, hake (Urophycis), and pollock (Pollachius), among others. Whitefish (Coregonidae) is also the name of several species of Atlantic freshwater fish.

Demersal fish, also known as groundfish, live and feed on or near the bottom of seas or lakes. They occupy the sea floors and lake beds, which usually consist of mud, sand, gravel or rocks. In coastal waters, they are found on or near the continental shelf, and in deep waters, they are found on or near the continental slope or along the continental rise. They are not generally found in the deepest waters, such as abyssal depths or on the abyssal plain, but they can be found around seamounts and islands. The word demersal comes from the Latin demergere, which means to sink.