When a crab is dying or dead, the histoxic acid in the crab's body will decompose to produce histamine. Histamine is a poisonous substance. As the death time prolongs, more and more histamine accumulates in the crab body, and the poisonous gas becomes more and more powerful. Even if the crab is cooked, this toxin is not easily destroyed.

Although the histamine content of frozen crabs is not as high as that of natural death, it cannot be ignored and it is best not to eat them