Dog-Fish

a general name applied to numerous species of fishes resembling small sharks. They are eighteen inches to eight feet long. They follow up schools of cod, herring, and mackerel, and other food fishes in hungry packs, whence their name. Fishermen dread them for the mischief they do, breaking nets, cutting lines, but chiefly driving away the schools of fish. The sea may be alive with mackerel and the fishermen reaping a harvest, when the back fins of a pack of dog-fish are seen cutting the water and all is over. The fish have gone elsewhere and must be sought anew.