How to distinguish "chilled fish" from "frozen fish"

"Iced fresh fish" is a fresh sea area. After salvaging, the whole fish is quickly frozen for preservation, and the freezing time does not exceed 72 hours. "Frozen fish" has been stored in the snow for more than 72 hours, and is generally a large deep-sea catch, such as Longli fish. Most of them have been processed, and the internal organs have been removed and processed into fish chops. Look at the fish eye. The eyeball of fresh fish is full and prominent, and the cornea is transparent and elastic; The eyeball is not prominent, the cornea is shriveled, and the eye is slightly turbid or bleeding; The stale fish eye collapses or dries up, and the cornea shrinks or ruptures. Second, look at the cheeks. Fresh fish gills are clear and bright red, and the mucus is transparent, which has the salty taste of marine fish or the earthy smell of freshwater fish, and there is no difference in smell; The gills of stale fish are brown or grayish white, with filthy mucus and unpleasant rancid smell. Third, look at the fish skin. Fresh chilled fish skin integrity, mucus transparent, shiny scales, close to the fish, not easy to fall off (except pomfret, large yellow croaker, small yellow croaker); The skin of stale fish is dull, the surface is covered with filthy mucus, and the scales are separated from the skin. Four pressure fish. Fresh fish is firm and elastic, the depression disappears immediately after finger pressing, there is no odor, and the muscle section is shiny; The stale fish is loose and easy to separate from the fish bones, and the depression formed by finger pressing can not be recovered, and the finger can even puncture the fish.