Also called green cod, black pollack, saith, and sillock. The three dorsal fins are low, the second the longest at the base, but shorter than the first anal fin. The lower jaw projects a little beyond the upper in the adult, scarcely at all in the very young, and is provided with a very small mental barbel, which may be so reduced as to be easily overlooked. The vent is situated vertically below the posterior half of the first dorsal fin. The upper parts vary from dark grey or olive to blackish, shading off into silvery white towards the belly; the lateral line is whitish; usually a dark spot in the axil of the pectoral fin, not visible when the fin is folded. Old specimens are darker than the young.
This fish grows to a large size; specimens a little over 3½ feet are on record, but the usual length is between 2 and 3 feet.
The range of the coal-fish is a very wide one, and nearly coincides with that of the cod, although of a somewhat more southern character, as it extends to both east and west coasts of the North Atlantic, and it is occasionally found in the Mediterranean. It is especially common in the north, though rarely entering the Baltic; it becomes rare south of the English Channel. Its limits of distribution appear to be between 46° and 80° lat. in the Western Atlantic, between 40° and 70° in the Eastern Atlantic. It descends to a depth of 70 fathoms.
The breeding season with us is said to begin in January, and to continue through February, March, and April; according to Brook, the spawning on the coast of Scotland may even begin in December. On the coast of Massachusetts the spawning period has been ascertained to be in November and December. Unlike the cod and the haddock, the coal-fish is, to a great extent, a surface-swimming fish, congregating together in large schools, and moving from place to place in search of food ; large specimens, however, prefer deep water, and rarely fall a prey to the sportsman.