Bluish complexion

Cyan may be caused by histamine poisoning in fish. After the death of animals such as shrimp, crab, and catfish, the protein in the body is rapidly decomposed to produce a large amount of histamine. Consumption of these aquatic products will increase the histamine content in the blood of the human body. The face and even the skin color of those who are improperly or allergic will appear bluish red, the whole body is uncomfortable, and sometimes accompanied by headache and strange itching.