Fresh fish meat is delicious and nutritious, but the fish has low-fat content, high water content, difficult to save, and easy to spoil. Once dehydrated and dead, it is easily affected by bacteria and quickly decomposes to produce trimethylamine and piperidine. Trimethylamine is Gas, easily soluble in water; piperidine is liquid with ammonia smell. So many people think of fishy smell when it comes to fish. There is a kind of greasy catfish in Italian cuisine. After fermentation, the smell is very strong, but many people I like it. It is used in mixing salad dressings to make pasta sauce. It is often seen that it should be a distant relative of ancient Greek and Roman seasoning fish sauce (Garum). The text is intended to explain:. ['Italians like heavy-smelling greasy catfish.', 'How does the fish smell.', 'Different people have a different cultural identity on the smell of fish.', 'Many people are more sensitive to the stench of fish.']