"Black" in the belly of fish: including marine fish and river fish, there is a thin black film on both sides of the belly, which is the most fishy and earthy part of fish, containing a lot of lipids, thick waist and lysozyme. Eating by mistake can cause nausea, vomiting and abdominal pain. According to other scientific research data, this black film is a gathering place of various harmful substances, which is caused by long-term pollution of toxic components such as bacteria, pesticides and dirt in water. Of course, eating it is harmful. So scrape off the "black" (film) after cutting the fish.

Although this black film in the belly of fish looks ugly, some people may still think it is dirty, but this black film has nothing to do with pollution and toxins. Because this film shows that black is natural and edible, there is no potential safety hazard. Therefore, it is misleading to say that the black film in the belly of fish is toxic and will cause harm to the body.

This black membrane in the belly of fish is called "peritoneal visceral layer" or "internal visceral layer", and its existence has a certain effect. It can reduce the impact of fish's abdominal wall and viscera on viscera, and also play a role in lubricating and reducing the direct friction of viscera. This shows that this layer of black film in fish belly is formed to protect internal organs.