A traditional way to clean a fish it so scale it and gut it. This method produces a whole fish and the head can be cut off or left on. Small fish such as bream in fresh water and croaker in salt water lend themselves to scaling, while bigger fish can be cleaned in other ways. Some recipes are done better with whole fish.
How to Scale and Gut a Fish
Keeping fish wet until it's time to scale them helps make removing the scales easier. Make sure the fish stay wet by putting them in a live well, which is an aerated container filled with water for transporting fish, or on a stringer in the water. A stringer is a cord with a pointed metal shaft on one end to slip through the gills of the fish. There is usually a metal ring on the other end to keep them from sliding off, but you should loop the line back through the ring on the first fish to attach it securely. Even better, put the fish on ice as soon as you catch them to keep them moist and help preserve their flavor.
To scale a fish, lay it on its side and rub the edge of a dull knife or spoon against the grain of the scales, working from tail to head. You can hold the fish by the head or purchase a clip board to hold it. Wearing a glove on your holding hand will keep the fish from slipping. The scales should peel off easily as you scrape against them. Work carefully around the fins so you do not stick a fin in your hand.
Some fish, such as trout and flounder, have tiny scales that are very difficult to remove and are okay to eat as is. The skin can be removed after cooking or skin and scales can be eaten without a problem.
To gut bigger fish, make a cut with a sharp knife from the vent opening to the head, and then scrape the guts out with a finger or a dull knife. Many people like to cut out the vent hole itself during this process for esthetic reasons; cut a V-shaped notch across the body of the fish to cut it out. If you're going to cut the head of the fish off, do that first and then make the cut up the belly of the fish. Cut from the top of the head around the back of the gill plate to the neck of the fish just below the eye in a semicircle, cutting all the way through the fish.
On small panfish like bream, crappie, and croaker, it's much more efficient to make a diagonal cut from the top of the head to just behind the vent across the fish and all the way through it. This removes the head and guts with one stroke of the knife, and it's very easy to remove any remaining guts in the body cavity. Cutting a fish in this manner loses very little meat.
After the Cleaning Is Done
Check all around the fish for remaining scales and scrape them off; then wash the fish with cold water to remove any loose scales and guts. Cook the fish immediately for the best flavor or put it in salt water in the refrigerator if you are going to cook it within a couple of days. Make sure the entire fish stays in the salt water so it doesn't dry out before you cook it.
You can freeze small fish whole, submerged in unsalted water if you want to keep them for several weeks. Cut the top out of a milk jug and put the fish in it; then cover it with water and freeze it. Don't use plastic bags because the fins will stick holes in the bag and make it leak.