Order the fish skinned, but head and tail left on. Cut off head and tail and remove fish from backbone. Cut fish in two inch pieces and set aside. Put head, tail and back bone, broken in pieces, in stew pan; add two cups cold water and bring slowly to boiling point, cook twenty minutes. Cut salt pork in small pieces and try out, add onion, and fry five minutes; strain fat into stew pan. Parboil potatoes five minutes in boiling water to cover; drain and add potatoes to fat, then add two cups boiling water and cook five minutes. Add liquor, drained from bones, then add the fish, cover and simmer ten minutes. Add milk, salt, pepper, butter and crackers, split and soaked in enough cold milk to moisten, otherwise they will be soft on the outside but dry on the inside.