If you are wanting to know how to clean a fish, first you need to decide how you are going to cook the fish. There are three basic ways to clean a fish:
1.) Leaving the fish whole, this is used when baking or grilling. You can remove the head or leave it on whatever preference you have.
2.) Cutting a fish into steaks is a good way to prepare small sharks, cobia, mackerel, and wahoo and can also be grilled or baked.
3.)You can learn how to fillet a fish though this is the most difficult but with a little practice you can have fillets that look like you bought them at a supermarket. Fillets can be grilled, baked, cut into chunks, or fried.
To leave the fish whole you need to first remove the scales of the fish.
After the scaling process you need to remove the head (optional).
Cut open the stomach cavity and remove all the goods inside.
Sometimes you can gain some knowledge on what else the fish might be feeding on by cutting open the stomach.
You will be surprised what you may find.
Whichever way you decide to clean your fish remember that they are slippery and the knife is sharp so be careful.
Also make sure you do the proper steps when freezing fish.