Fish have far more amino acids than chickens, cattle, or pigs. This is where that "fishy" taste comes from. At the same time, it is relatively easy for bacteria to become attached to the gills or digestive organs of fish. Once a fish dies, the enzymes quickly begin to decompose the flesh, allowing the bacteria to flourish.
海鮮的體內含有較雞、牛、豬肉更多的氨基酸酵素，這是它鮮味的來源，然而魚類的鰓及消化器官原本就容易附著細菌，一旦海鮮死亡之後，酵素快速將魚體分解，使得細菌快速繁殖，這時若沒有妥善的冷藏技術，那海鮮就會變成海腥了。