Fish can be Pan fried, BBQ Grilled, Poached, Breaded, Steamed, Broiled, Baked and if Micro-waved then figure about 8 to 10 minutes per one inch of thickness of the thickest part of the fish. 
When cooking a whole fish it’s best to put slices in the fish on both sides but not deep enough to cut through the bone. Then rub with oil and add spices. It is not necessary to slice filets.

How to Grill Fish - Barbecue
When grilling fish on an outdoor, hot coal or gas barbecue, keep a close watch. Fish only takes a five minutes or so per side to cook. If the fillets are an even thickness they may not require flipping so grill on one side only.
Brush the fish lightly with olive oil or cooking oil.
Place fish on the grill, away from the hottest part of the fire. Don't try to lift up the fish right away as it will be stuck to the grill.
After a few minutes, start checking for color and
if done. Flip the fish over if needed.
*Serve with some prepared sauce spooned over it.

How to Poach Fish
Poached Fish (if frozen let it thaw out a day or two in the refrigerator.) When ready to cook let it set out 20-30 minutes to help it reach room
temperature. 
When poaching fish, use a vegetable or chicken stock or broth, add some aromatic herbs and spices.
Bring the liquid to a simmer, and keep it there (never boil.) An ideal poaching temperature is between 165 and 180 degrees F (74 to 82 degrees C).
There should be enough liquid to completely cover the fish. Use a pan big enough to lay each piece of fish down flat.
Cook for about 5-7 minutes or until the fish is just done without being overcooked. Carefully remove the fish.
Serve after spooning a tablespoon of prepared sauce over it.
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How to Steam Fish
Rub the fish with oil then spices; garlic salt, paprika, Italian herbs, and black pepper.
Steaming is a delicious and gentle way to cook fresh fish. It only takes 10 minutes in a bamboo steamer, or fifteen to 20 minutes in a fry pan with a small amount of water added and the pan must be covered (check water level and add more water in small amounts if needed. Steam produces moist, flaky fish every time.
After done serve with some prepared sauce spooned over it.

How to Broil Fish
Broiling is great for fast results. It browns the fish nicely, For easy cleanup, line the broiler pan with a piece of aluminum foil. Remember to always keep the oven door open when broiling, the reason being that a closed door will bake items. Remember to always preheat an oven/broiler.
Prepare the fish by rubbing with oil and spices, place it flat and broil one side then flip and broil the other. About 7 minutes per side.
Remove and serve.

How to Bake Fish
Rub fish in oil and spices,
Place into a baking dish, for oven baking. bake at 375 for 15-20 minutes or until done.

How to cook breaded fish for oven baking or pan frying it
Baking breaded fish allows you to get the satisfying crunch of fried fish. Always defrost the fish if frozen before cooking it.
Breading Ingredients:
Flour
Bread crumbs or cracker crumbs or crushed cornflakes
Egg, beaten.
Water or Milk
Crush cracker crumbs or bread crumbs or corn flakes in a bowl. If crumbs are not seasoned, then season to taste.
In another bowl, beat an egg together with a bit of water or milk. 
In a plate spread out some flour.
Coat the fish in the flour then dip the fish in the egg mixture to coat it, then dip it in the seasoned bread crumb, cracker crumbs or corn flakes mixture.
Place into a baking dish, for oven baking. bake at 375 for 15-20 minutes or until done.
To pan fry the fish instead of baking it: add oil to fry pan and heat using just under a medium heat as you want to brown the breading slowly without burning it. Allow to fry about 10-12 minutes each side flipping it
 only once.