The issue of seafood safety was once all the rage, and the public began to feel at a loss. What fish is the safest? A reporter connected with Professor Wang Cunxin from the Institute of Oceanology of the Chinese Academy of Sciences, Professor He Jiguo and Professor Ma Changwei from the College of Food Science and Nutritional Engineering at China Agricultural University, and Luo Jianren, Deputy Director of the Pearl River Fisheries Research Institute of Guangdong Province, to answer questions for everyone.
Question 1: It is now said that water pollution is severe. Is it best not to eat fish at all?
He Jiguo believes that currently, due to industrial waste being discharged into the sea, many marine waters are polluted, making fish living in them susceptible to mercury contamination. However, the public does not need to throw the baby out with the bathwater. As China's import inspection and quarantine efforts have increased, as long as the fish are sold through regular channels, they are generally safe to eat.
Wang Cunxin stated that the fish currently on the market are either near-shore farmed or deep-sea farmed, but most live in net cages. Unless the sea area is affected by red tide or other pollution, they are generally not easily infected with toxins. So far, no cases of adverse reactions from consuming seafood with excessive drug residues have been found in China. In addition, there is the issue of consumption quantity; some harmful drugs need to reach a certain amount to cause harm to the human body.
Question 2: Which is safer, deep-sea fish or freshwater fish?
Wang Cunxin said that in terms of safety, the order should be marine fish, desalinated farmed marine fish, and then freshwater fish. This is because seawater has high flow and salinity, which has a natural bactericidal effect. Among them, deep-sea fish like salmon are safer than near-shore fish, and their nutritional value is also unmatched by other fish. River water is relatively more susceptible to pollution, with higher parasite content and a higher infection rate. The safety of desalinated farmed marine fish falls in between.
Ma Changwei, on the other hand, stated that whether it's marine fish or freshwater fish, the key is whether the farming environment meets the standards. As long as the fish are not farmed or caught in polluted water, they are safe. Currently, the food safety traceability system is popular internationally. Every fish has a history record from its birth, growth, to how it was caught and processed, until it reaches the table, forming a complete chain of supervision.
Question 3: How to choose safe fish?
He Jiguo suggests,
1. Observe the fish's shape. Fish heavily polluted may have abnormal morphology, such as a large head and a small tail, a curved spine or even deformities. Some may have yellow skin and a greenish tail.
2. Look at the fish's eyes. A fish with full, protruding eyes and a clear, transparent cornea is fresh. Fish with non-protruding eyes, wrinkled corneas, or bloodstains inside the eyes are not fresh.
3. Smell the fish's gills. The gills of a fresh fish are bright red, the mucus is transparent, and it has the salty smell of marine fish or the earthy smell of freshwater fish. The gills of an unfresh fish are dark, gray-red or gray-purple, and the mucus has a foul, fishy smell.
4. Feel the fish's body. The surface of a fresh fish has transparent mucus, the scales are shiny and adhere closely to the body, and are not easy to fall off. The mucus on an unfresh fish is mostly opaque, the scales are dull, and they are easier to fall off.
5. Press the fish's flesh. The flesh of a fresh fish is firm and elastic; the indentation from a finger press disappears immediately, and there is no strange odor. The flesh of an unfresh fish is slightly loose, the indentation from a finger press disappears slowly, and there is a slightly fishy, foul smell.
6. Look at the fish's abdomen. The abdomen of a fresh fish is not bloated, and the anal opening is white and sunken. The anal opening of an unfresh fish is slightly protruding.
He Jiguo also taught everyone a trick for picking fish: when choosing freshwater fish, try to choose "small" fish, which are at the bottom of the food chain, such as grass carp and bighead carp. They generally feed on aquatic plants, so compared to fierce carnivorous fish like grouper, sea bass, and mandarin fish, their harmful substance content is relatively low, and thus they are relatively safer. For deep-sea fish, since they are generally larger, eating "small" fish is safer than eating "big" fish. Here, "small" refers to both young age and smaller size. The larger the fish, the higher its toxin content.
After buying live fish, you can keep them in clear water for a day or two; if the fish is already dead, soak it in clear water for at least an hour. Fish should not be stored for a long time. When cleaning, the gills must be removed and washed thoroughly. In addition, parts of the fish with high fat content are where harmful substances are most likely to accumulate, starting with the head, followed by the center of the abdomen, which are relatively more polluted. When cooking, it is also best to cook or steam thoroughly and not to eat it raw.