Fish is a kind of aquatic vertebrate with variable temperature. It has bone scales on its body surface, breathes through gills, swims through the swing of its tail and trunk, and feeds on the upper and lower jaws. It belongs to the vertebrate subfamily of Chordata. Vertebrates are generally divided into fish (53%), birds (18%), reptiles (12%) and mammals (9.
According to the statistics of the late Canadian scholar Nelson1994, there are 246 18 species of fish * * in the world, accounting for more than half of the named vertebrates, and new fish species are constantly being discovered, with an average of about 150 species per year, which should increase by more than 1500 species in more than ten years.
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Nutritional components of fish:
1. is rich in whole protein. Fish contains a lot of protein, such as yellow croaker 17.6%, hairtail 18. 1%, mackerel 2 1.4%, silver carp 18.6% and carp/kloc-.
2. Low fat content, mostly unsaturated fatty acids. The fat content of fish is generally low, and most of them are only 1% ~ 4%, such as yellow croaker 0.8%, hairtail 3.8%, mackerel 4%, silver carp 4.3%, carp 5%, crucian carp 1. 1% bighead carp (.
3. The content of inorganic salts and vitamins is high. Marine fish and freshwater fish are rich in sulfur and also contain inorganic salts such as phosphorus, calcium and iron. Fish also contains a lot of vitamin A, vitamin D, vitamin B 1 and nicotinic acid. These are all nutrients that the human body needs.
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