Why Does Fish Often Smell Fishy? The Real Reason Many People Don’t Know

Fish usually has a stronger fishy odor compared to other types of food such as pork or beef. If not prepared properly, this smell can affect the quality of the dish.

Why does fish often smell fishy?

In reality, freshly caught fish usually smells less fishy than fish that has been kept for a while. Fish meat changes over time and develops a fishy odor. The reason is that fish contains trimethylamine NH(CH3) – an amine compound responsible for the typical fishy smell. In freshly caught fish, the amount of this substance is low, so the odor is mild. However, in fish stored for a longer period, trimethylamine levels increase, making the smell more noticeable.

Generally, fish that is cooked immediately after being caught tastes the best, retaining its natural sweetness with little to no fishy odor. For example, in some coastal provinces, locals often prepare a “fishing boat soup” by cleaning freshly caught fish and dropping it straight into boiling water. With this method, the fish doesn’t require elaborate preparation or extensive odor removal, yet the soup remains free of fishiness.

On the other hand, if you buy pre-processed fish or frozen fish, home cooks often need to use ingredients like vinegar, lemon, ginger, salt, or rice wine to reduce the smell. Sometimes, even after thorough preparation, the fish may still smell – often because it isn’t fresh.

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Tips to Cook Fish Without the Fishy Smell

1. Clean the fish properly
Remove fins, scales, guts, and gills. Wash away the blood inside the belly and scrape off the dark membrane, as these are major sources of odor. Then, you can soak and rinse the fish with coarse salt, rice water, vinegar, lemon juice, or ginger wine.

2. Use boiling water for cooking
When cooking fish dishes, always use hot water. If you add cold water, the dish often turns out fishy.
Hot water makes the fish skin firm quickly, preventing amino acids from dissolving into the broth, thus reducing odor.
Also, leave the pot uncovered while cooking so that the fishy-smelling amines can evaporate with the steam. If you need to add more water, always use boiling water.

3. Neutralize odor with sour ingredients
Use sour ingredients like starfruit, tamarind, fermented rice, tomatoes, pineapple, vinegar, or pickled fruits to reduce fishiness. These contain organic acids that neutralize the alkalinity of trimethylamine.

4. Remove odor with cooking wine
Adding cooking wine or white rice wine when preparing fish helps dissolve and eliminate trimethylamine.

5. Add aromatic herbs and spices
Aromatic herbs are essential in many fish dishes. Common ones include green onions, dill, Vietnamese coriander, cilantro, and rice paddy herb. Spices like ginger, garlic, chili, and pepper also enhance flavor and mask odors.

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The most important factor in cooking fish is choosing fresh ingredients. The fresher the fish, the less fishy it smells. Fish that has been stored too long after being caught will undergo chemical changes that intensify the odor.