The haddock or offshore hake is a marine fish distributed on both sides of the North Atlantic. Haddock is a popular food fish, widely fished commercially.
The haddock is easily recognized by a black lateral line running along its white side (not to be confused with pollock which has the reverse, ie white line on black side) and a distinctive dark blotch above the pectoral fin, often described as a "thumbprint" or even the "Devil's thumbprint" or "St. Peter's mark".
Haddock is most commonly found at depths of 40 to 133 m, but has a range as deep as 300 m. It thrives in temperatures of 2° to 10°C (36° to 50°F). Juveniles prefer shallower waters and larger adults deeper water. Generally, adult haddock do not engage in long migratory behavior as do the younger fish, but seasonal movements have been known to occur across all ages. Haddock feed primarily on small invertebrates, although larger members of the species may occasionally consume fish.
