Fish is rather popular among many people. It not only has good taste, but also contains abundant nutrients, such as protein, vitamin D, thiamine, riboflavin, nicotinic acid and some mineral substances like calcium, phosphorus and iron. The content of protein contained in fish is two times higher than that in pork. The content of fat is relatively low, but the fatty acid contained in fish can decrease the blood sugar, protect the heart and prevent the cancer for the human body. In addition, the vitamin D, calcium and phosphorus can effectively help people prevent the osteoporosis. 

In order to keep healthy and improve the physical conditions, people should choose the right kinds of fish according to the concrete situations of their own bodies. Thus, the medical property and the effect of nutrients can be realized completely. Different kinds of fish play different roles in helping people improve the physical conditions. For example, crucian plays an important role in eliminating the edema, improving the secretion of breast milk and removing the internal heat. It can effectively treat gastroptosis, rectocele and some other diseases. Hairtail can deal with indigestion, persistent hepatitis and chronic hepatitis. In addition, it can keep the skin elastic and soft. Black carp contains many trace elements, such as zinc, selenium and iron, and it can help people prevent and resist the cancer. Black carp can also effectively deal with headache, malaria, dermatophytosis and asthenia for people.

It is necessary for people to choose suitable kinds of fish, which also means that the patients with various diseases should avoid certain kinds of fish. The patients with hemorrhagic diseases should not eat fish. Such diseases are mainly caused by the decrease of blood platelets, the lack of vitamin K, hemophilia and so on. 20-carbon 5-gadoleic acid contained in fish can restrain the agglutination of blood platelets so as to worsen the symptoms of the diseases. The patients with tuberculosis should also avoid some kinds of fish. The patients have to take isonicotinic acid hydrazide in order to maintain the normal life activities. However, the intake of certain fish can cause the symptoms of allergy, such as headache, sickness, diarrhea, dyspnoea and even cerebral hemorrhage. The patients with gout should also not eat fish excessively. Fish contains purine substances, while gout is caused by the disorder of metabolism of purine inside the human body. Therefore, the patients should avoid some kinds of fish which are harmful to the health of the patients.