In the most scientific and biological sense, the primary difference between the cod and haddock is their species type. Both fishes actually belong to the same family gadidae, but branch out into different genus, with the haddock under the melanogrammus genus, with the cod being a member of the genus gadus. Overall, this difference in species between the cod and haddock largely accounts for the difference in appearance, eating habits, and habitat.
These fish can be very similar in appearance, but the most apparent difference between the two fishes is their lateral lines running from the head to the tail. The cod has a pale, whitish lateral line, while the haddock has a dark black lateral line, along with some blotches on its pectoral fin located as the side of the head. The haddock has a longer and more pointed primary dorsal fin, located on the fish’s back nearest the head, than that of the cod’s. The haddock’s tail has also a more concave appearance than the cod’s blunter tail-end. Both fishes also differ in color: the cod appears to have a greenish, yellowish tinge, while the haddock has a grayish, silvery shade.
Both fishes live on similar ranges, such as in the North Atlantic and the Gulf of Maine. Their depth of habitation, however, differ in that the cods live in shallower waters than the haddocks that seek deeper waters. Cods are aplenty in 5 to 10 fathoms (9.14 to 18.28 meters) deep, while haddocks populate the waters from 20 to 70 fathoms (36.57 to 128.01 meters) deep. This is probably why cods are more prone to overfishing than the haddocks. In fact, the World Wide Fund (WWF) listed the cod as an endangered species in the year 2000, and in 2010, the Atlantic cod was placed on the Greenpeace International’s “seafood red list.”
In terms of their eating habits, the cod and haddock eat similar foods such as sea cucumbers, worms, brittle stars, and mollusks. The difference is that the cod eats bigger-sized clams and crabs, while the haddocks do not. Haddocks also eat more worms than cods, probably because sea worms are plentiful near the bottom of the ocean. Cods, on the other hand, would even attempt to catch little sea ducks near the water surface.
An expert fisherman or angler may know the difference between the cod and haddock, but even chefs can detect the difference in terms of texture and text. The cod is slightly softer than the haddock when gently pressed, an indication of a difference in the meat texture. The cod meat is moister and plumper, while the haddock can have a flaky and dry consistency. The cod and haddock both taste similarly, but many cooks say the haddock has a sweeter flavor.