White fish have fat secreted in the liver. Examples: cod, haddock, trout, flounder, smelt, perch, etc.
Oily fish have fat distributed throughout the flesh. Examples: salmon, eels, mackerel, bluefish, swordfish, shad, herring, etc.
Cod belongs to one of the most prolific fish families (Gadidoe), and is widely distributed throughout the northern and temperate seas of both hemispheres. On account of its abundance, cheapness, and easy procurability, it forms, from an economical standpoint, one of the most important fish foods. Cod have been caught weighing over a hundred pounds, but average market cod weigh from six to ten pounds; a six-pound cod measures about twenty-three inches in length. Large cod are cut into steaks. The skin of cod is white, heavily mottled with gray, with a white line running the entire length of fish on either side. Cod is caught in shallow or deep waters. Shallow-water cod (caught off rocks) is called rock cod; deep-water cod is called off-shore cod. Rock cod are apt to be wormy. Cod obtained off George’s Banks, Newfoundland, are called George’s cod, and are commercially known as the best fish. Quantities of cod are preserved by drying and salting. Salted George’s cod is the best brand on the market. Cod is in season throughout the year.
Cod Liver Oil is obtained from cods’ livers, and has great therapeutic value. Isinglass, made from swimming bladder of cod, nearly equals in quality that made from bladder of sturgeon.
Haddock is more closely allied to cod than any other fish.
It is smaller (its average weight being about four pounds), and differently mottled. The distinguishing mark of the haddock is a black line running the entire length of fish on either side. Haddock is found in the same water and in company with cod, but not so abundantly. Like cod, haddock is cheap, and in season throughout the year. Haddock, when dried, smoked, and salted, is known as Finnan Haddie.
Halibut is the largest of the flatfish family (Pleuronectidæ), specimens having been caught weighing from three to four hundred pounds. Small, or chicken, halibut is the kind usually found in market, and weighs from fifteen to twenty-five pounds. Halibut are distinctively cold-water fish, being caught in water at from 32° to 45° F. They are found in the North Atlantic and North Pacific oceans, where they are nearly identical. The halibut has a compressed body, the skin on one side being white, on the other light, or dark gray, and both eyes are found on the dark side of head. Halibut is in season throughout the year.
Turbot (called little halibut) is a species of the flatfish family, being smaller than halibut, and of more delicate flavor. Turbot are in season from January to March.
Flounder is a small flatfish, which closely resembles the sole which is caught in English waters, and is often served under that name.
Trout are generally fresh water fish, varying much in size and skin-coloring. Lake trout, which are the largest, reach their greatest perfection in Lakes Huron, Michigan, and Superior, but are found in many lakes. Salmon trout is the name applied to trout caught in New York lakes. Brook trout, caught in brooks and small lakes, are superior eating. Trout are in season from April to August, but a few are found later.