This fish, which grows to a length of three feet, is recognisable among the species with the base of the anal fin considerably longer than that of the second dorsal, by its very prominent lower jaw, the chin, which is deprived of a barbel, extending forward a good deal beyond the end of the snout, and by the position of the vent, which, owing to the somewhat longer first anal fin, is situated vertically below the anterior half of the first dorsal fin, instead of being below its posterior half, as in the coal-fish. The eye is also larger in proportion than in the latter species. The colour is brown or olive above, the lateral line darker, yellowish, or golden below, often with a dark spot superiorly in the axil of the pectoral fin.
The pollack, or lythe, occurs on the coasts of Europe, as far south as the western parts of the Mediterranean. It is extremely common on our rocky coasts. It is, for a considerable period of its existence, a surface fish, and is usually found not far from land, chasing schools of young cod and herrings; but full-grotfn examples frequent the deeper waters offshore. The breeding season, on the British coasts, lasts from December till May, taking place earlier in the north than in the south.
A very full account of the external and osteological characters of the coal-fish and pollack, compared with the cod, will be found in a paper by Dr. H. C. Williamson, published in Part III. of the Twentieth Annual Report of the Fishery Board for Scotland, 1902, pp. 228-287, pis. iv.-xi.