Pollock, or Pollack, any of three species of fish. “Pollock” is the usual spelling when referring to the common pollock (found along both coasts of the North Atlantic Ocean) and to the walleye pollock (found along both coasts of the North Pacific Ocean). “Pollack” is the usual spelling when referring to the European pollack (found along the eastern coast of the North Atlantic).

A pollock is greenish brown above and whitish or yellowish below, with a projecting lower jaw and a slightly forked tail. Pollocks grow to more than three feet (90 cm) in length and more than 40 pounds (18 kg) in weight. Pollocks travel in schools and eat smaller fish and shellfish. The common pollock and the walleye pollock are commercially important food fish.

Pollocks belong to the cod family, Gadidae. The common pollock is Pollachius virens; the European pollack, P. pollachius; the walleye pollock, Theragra chalcogramma.