A haddock is a fish that lives in cold northern seas, especially the North Atlantic. It has white flesh and is often eaten fried, smoked, or baked. In Britain, fish and chips is sometimes haddock, not only cod. The two fish look and taste similar, so shops and menus mix them up more than textbooks admit. Haddock usually has a dark line along its side — that is the mark people use to tell it apart. It is an ordinary food-fish word, not a fancy one. Though actually, in many places people just say “white fish” and never know which one they are eating.