Cold-water fish cod: is it a sea fish or a river fish? Prices and how to tell real from fake when shopping in supermarkets

Cod, also known as bighead green, bigmouth fish, bighead fish, walleye pollock, shuikou, wide-mouth fish, bighead stink, stone-gut fish, is one of the fish with the largest annual catch in the world. So is it a sea fish or a river fish? How much does it cost per jin? Is what supermarkets sell the real thing? According to the Guangzhou seafood market, the market price of cod is about 60-100 yuan per jin, and it depends on the place of origin and the type of cod; for example, black cod from Alaska in the United States is more expensive, at about 130 yuan per jin.

Is cod a sea fish or a river fish?

1. True cod refers to fish of the genus Gadus, divided into Atlantic cod, Greenland cod and Pacific cod. Under the order Gadiformes there is the family Gadidae; the usual concept of cod has expanded to include fish of the family Gadidae, with more than 50 species. Most of them are distributed in the continental shelf waters of the northern Atlantic Ocean. Important species include haddock, blue whiting, saithe, whiting, ling and walleye pollock. Cod is one of the fish with the largest annual catch in the world and has important food and economic value.

2. Cod is distributed in the North Pacific; on both sides of the North Atlantic it generally lives near the bottom, ranging from nearshore to deep-sea areas. It is native to the cold waters of the North Atlantic from Northern Europe to Canada and the eastern United States. The world's main cod-producing countries are Canada, Iceland, Norway and Russia, and in Japan the producing areas are mainly Hokkaido.

In China it is mainly distributed in the Bohai Sea, the Yellow Sea and the northern East China Sea. The main fishing grounds are in the northern Yellow Sea, southeast by east of Shandong Cape, and the southern and southeastern sea areas of Haiyang Island.

3. Cod is a cold-water bottom-dwelling fish that feeds on invertebrates and small fish. In summer and autumn it inhabits the cold-water area of the Yellow Sea, and in winter it migrates to overwinter in coastal muddy-bottom areas at a water depth of 50-80 m. Most cod live in the cold seas of the northern Pacific and Atlantic at water temperatures of 0°C-16°C.

Cod feeds on other fish and invertebrates; it eats a lot and grows fast, reaching 1 m in size in about 10 years. It has a large appetite and is a voracious migratory fish. Because it lives in groups, it is very easy to catch, and it has been a fairly famous food fish since ancient times. Its reproductive capacity is strong: a female about 1 m long can produce as many as 3 million to 4 million eggs at a time. In the Yellow Sea the reproductive period is January to February, with 340,000 to 830,000 eggs, demersal eggs, 0.98-1.05 mm in diameter.

Is the cod sold in supermarkets real?

Generally, supermarket freezers have many kinds of “cod”, with five or six labels related to cod on a single freezer, including “Alaska silver cod”, “Alaska true cod”, “frozen true cod”, “frozen walleye pollock”, etc. Some cost 208 yuan per bag, and some 28 yuan per bag. These cod include imported and domestic ones; imported ones are expensive and domestic ones are cheap. Silver cod is cod, while walleye pollock is not cod, but another fish.

So for consumers, the thing to watch out for most is water cod. Water cod has nothing whatsoever to do with cod, but because it looks similar, it is often passed off as cod. The vast majority of water cod on the market is oilfish, which belongs to the order Perciformes. This fish is also imported, but its price is 6-10 times cheaper than cod and silver cod, because abroad they are used to extract animal oil rather than for eating, and residents of developed countries do not eat this fish. Oilfish contains a large amount of animal fat that the human body cannot absorb; its animal fat content is 20 times that of cod. This animal fat is harmful and not beneficial to the human body, and some infants and young children whose body functions are not yet fully developed may have abnormal bowel movements after eating it.

Appendix: How to choose cod

1. Appearance: cod meat is white in color, without that kind of particularly thick and particularly obvious red line, and the scales are dense, one overlapping another.

2. Skin: after cod is thawed, the skin feels very smooth, like a layer of mucus film; this is real cod.

3. Scales: when choosing cod, choose one that has not been scaled, because cod is generally sold unscaled.

4. Taste: cod is a deep-sea fish, and its texture is somewhat chewy, like crab leg meat; if it is soft and mushy, it is absolutely fake.