This section is from the book "Mrs. Allen's Cook Book", by Mrs. Ida C. Bailey Allen. See also: The Conscious Cook: Delicious Meatless Recipes That Will Change the Way You Eat.
If the fish must be scaled, first dip it in boiling water, and then begin at the tail and scrape with a blunt knife. Clean, and draw as soon as the fish is taken from the water. After removing the entrails be very sure that no particles remain close to the backbone. Wash the fish quickly all over, drain it, and let it stand upon the ice, if possible until time to cook it. However, as the fish odor is liable to permeate the ice-box, wrap the fish closely in oiled paper, and lay it on the ice. If fish is frozen, it must first be thawed out in cold water, then cooked at once.
Boning fish is a simple process that need not take long, if one works rapidly and with concentration. At the same time boned fish is certainly much safer to eat, and far more enjoyable, than fish with the bones left in it.
To remove the bones, begin at the tail end, slip the knife, which should be thin and sharp, between the flesh and the bones working up the backbone. Do this on both sides. If the fish is small, like flounder or sole, each side forms one fillet; if large, like shad or bluefish, the fish is not separated, but is stuffed or broiled or cooked as may be desired. Fillets of halibut are made from halibut steak, which are cut crosswise of the fish, and which separate naturally into four sections. Haddock and cod are also sliced and separated in the same manner.
The fat of red-blooded fish is distributed evenly throughout the flesh, making them moist and rich; to this end they are best not fried, but should be cooked by some other method which will not introduce excess fat. White-blooded fish are dry in texture because the fat is collected in certain portions, so they should be cooked by methods which introduce fat, as baking in milk or braising; if frying is to be done, these fish are well adapted to it. Olive oil is the best frying fat, clean beef drippings being the next choice. Lard is very unsatisfactory unless deep fat frying is to be done.