The fishy odor primarily originates from amine compounds found in the slime, blood, and dark membrane within the fish's belly. According to culinary experts, if these elements are not thoroughly removed before washing, the dish will lose its natural flavor.

Below are common mistakes when preparing fish.

Washing only with cold water

The idea that "the longer you wash, the cleaner it gets" is a common misconception. Cold water only dilutes the outer layer of slime but cannot remove it from the fish skin, especially for smooth-skinned fish like catfish, basa, or lang. When this slime dissolves but is not completely scraped off, the odor-causing compounds spread across the entire surface, making the fish smell worse.

Solution: Before rinsing with water, use wood ash, flour, or coarse salt to rub and remove the slime. For smooth-skinned fish, pouring hot water over the fish to coagulate the slime, then scraping it off, is the most effective method.

Illustrative photo: Bui Thuy

Overlooking the dark membrane and clotted blood

Many people focus only on cleaning scales and slime, neglecting the dark membrane lining the abdominal cavity and the clotted blood along the spine. These areas harbor bacteria and concentrate the strongest fishy odors. If the membrane is not scraped clean and all clotted blood is not rinsed away, the fish will still have an unpleasant smell, even after thorough cooking.

Misusing lemon, vinegar at the wrong time

Acids in lemon, vinegar, or wine can neutralize odor-causing amine compounds, but they are only effective after the fish is free of slime.

If fish is soaked in an acidic solution before removing the slime, the chemical reaction can denature the skin's surface, trapping the fishy smell more effectively. Additionally, soaking for too long will make the fish flesh mushy, diminishing its sweetness and characteristic aroma during cooking. The correct procedure is: Remove slime and dark membrane – Rinse thoroughly – Deodorize with acid/wine (if necessary) – Pat dry.

Not patting dry before cooking

Water remaining on the fish's surface acts as a solvent that retains the fishy odor. During cooking, especially frying, this water causes oil to splatter and the temperature to drop suddenly, making the fish take longer to cook and preventing the fishy smell from evaporating. Always use paper towels or a clean cloth to pat the fish dry before placing it in a pan or pot.

Incorrect thawing methods

Allowing fish to thaw at room temperature or soaking it directly in water for too long causes cellular fluids to leak out, carrying away nutrients and creating conditions for bacterial growth, which leads to unpleasant odors. It is best to thaw fish slowly in the refrigerator's cool compartment or under a gentle stream of running water (sealed in a bag) to preserve the freshest meat texture.

Bui Thuy