HAG-FISH, GLUTINOUS HAG, or BOREZ (MyXine), a marine fish which forms with the lampreys one of the lowest orders of vertebrates (Cyclostoniata). Similar in form to a lamprey, it is usually found within the body of dead cod or haddock, on the flesh of which it feeds after having buried itself in the abdomen. When caught, it secretes a thick glutinous slime in such quantity that it is commonly believed to have the power of converting water into glue. It is occasionally found in the North Atlantic and other temperate seas of the globe.