Ninety random samples of fresh fish (Claris gariepinus, Oreochromis niloticus and Mugil cephalus, 15 of each) and shellfish (Oyster, Shrimp and Crab, 15 of each) were collected from different fish markets in Kalyobia governorate, Egypt, for determination of histamine and cadaverine levels in their tissues. The obtained results revealed that, the mean value concentrations of histamine in fish samples were 21.