In the dorsal fin they have from 17 to 20 rays, and in the anal fin from 16 to 18; there are from 53 to 59 scales in the lateral line and 54 to 56 vertebrae in the vertebral column.
HADDOCK (Gadus aeglefinus), a fish which differs from the cod in having the mental barbel very short, the first anal fin with 22 to 25 rays, instead of 17 to 20, and the lateral line dark instead of whitish; it has a large blackish spot above each pectoral fin - associated in legend with the marks of St Peter's finger and thumb, the haddock being supposed to be the fish from whose mouth he took the tribute-money.
In some individuals the dorsal fin is only half its normal length, in others entirely absent; in others the anal fin has a double spine; in others all the fins are of nearly double the usual length.
In the cod and haddock the base of the first anal fin is not, or but slightly, longer than that of the second dorsal fin; in the whiting, pout, coal-fish, pollack, hake, ling and burbot, the former is considerably longer than the latter.
Sprats are very often confounded with young herrings, which they much resemble, but can always be distinguished by the following characters: they do not possess any teeth on the palate (vomer), like herrings; their gill-covers are smooth, without the radiating striae which are found in the shad and the pilchard; the anal fin consists of .from seventeen to twenty rays, and the lateral line of forty-seven or forty-eight scales.