Using fish scissors or kitchen shears, carefully cut off the fins.
Holding the fish by the tail as tightly as you can and using a fish scaler, the edge of a spoon, or the back of a knife, remove the scales. Scrape up from the tail to the head, using short, firm strokes. Remove the scales from the entire fish. If the fish is very slippery, wrap a clean kitchen towel around your hand to help with the grip. This tends to be a very messy operation, so make sure that the work surface is covered for easy disposal of the slippery scales. The whole process can also be done in a kitchen sink to facilitate cleanup.
Using the scissors or a very sharp chef’s knife, open the belly from the anus to the gills.
Using a sharp knife or scissors, cut off and discard the gills.
Using your fingertips, carefully pull out the entire intestinal tract. If a roe sack (fish eggs) is evident, carefully remove it and set aside for cooking with the fish.
Using a spoon, carefully scrape out any viscera that remain in the cavity.
Thoroughly rinse the cavity under cold running water. If serving whole, the fish is ready to be cooked. If cutting into fillets, further butchering is required.