To remove the skin, grasp the tail using a towel or glove, slit strips with a knife, and peel back the skin with pliers.
To remove the head, cut the flesh on both sides with a knife. If the fish is small, slice directly through the spine. For a larger fish, place a knife between vertebrae and tap the back of the knife with a hammer.
To fillet, use a sharp, thin knife. With the catfish lying on its side, insert the knife behind the gills, and cut in an arc down to just above the backbone. Continue cutting parallel to the backbone toward the tail. Bring the knife up at the tail and remove the fillet.
To make steaks, place the catfish on its side. With a sharp knife, cut slices 3/4 to 1/2-inch (1.9 to 1.25cm) thick perpendicular to the spine. Tap the back of the blade with a wooden mallet to cut through the spine.
To minimize any muddy taste, marinate fish in lemon juice or buttermilk for 30 minutes before cooking.
The secret to successful catfish cookery is to not overcook. Whichever of the following cooking methods you choose, your catfish will be cooked when its flesh becomes opaque and can easily be pierced with a fork.
Rinse fish and pat dry with a paper towel. Place whole fish, fillets, or steaks in a baking pan and cover with a sauce made of liquid, herbs, spices, and vegetables. Bake in an oven preheated to 400F (200C) until a knife slice in the thickest part reveals the flesh to be opaque but still moist.
Place fillets or steaks directly on greased grill, 4 to 6 inches (10 to 15 cm) above prepared coals or fire. Baste with butter, oil, or marinade, and close the hood of grill. Cook until opaque and moist on the inside--6 to 8 minutes for fish less than 1-inch (2.5cm) thick, and 10 to 15 minutes for fish larger than 1-inch (2.5cm) thick.
Rinse catfish and pat dry with a paper towel. Dredge in flour and seasonings. Shake off any excess flour. Heat frying pan until hot. Add butter or oil, place fillets in pan, and cook, turning once, until opaque but still moist in the center--2 to 10 minutes, depending on the size of the fish.
Pour oil into a wok or deep fryer; it should be at least 1 1/2 inches (3.8 cm) deep. The cooker should be less than half full of oil. Heat oil to 375 F (190C), using a thermometer to monitor temperature. Cut catfish into similar-sized pieces, 1 1/4 to 1 1/2-inch (3 to 3.8cm) across. Dip in batter, drain, then slip catfish pieces into hot oil. Cook until brown, about 2 to 3 minutes.
Bring poaching liquid, consisting of water, broth, herbs, and spices, to a simmer. Slip in skinless fillets, then cover pan and keep liquid at a simmer for about 8 minutes per inch (2.54cm) of thickness.
Rinse catfish fillets or steaks and pat dry with a paper towel. Coat fish with flour, crumbs, or cornmeal if desired. Place fish on a rack above a baking dish. Preheat broiler and adjust oven rack so fish is 3 to 4 inches (7.6 to 10cm) from the element. Broil, turning once, until the fish is opaque but still moist in the center--about 3 to 10 minutes, depending on size of the fish.