When selecting live fish, you can determine its vitality by its appearance, swimming state, and reaction to the external environment. A healthy fish has complete, intact mouth, eyes, gills, scales, and fins, without any signs of disease or injury. Its body surface is free of blood spots or holes, and it is full of vitality. Fish in good condition generally swim normally in the lower layer of the water. When touched by hand in the water, they react quickly and can break free and swim away. Fish in poor condition stay in the upper layer of the water, swimming with their mouths near the surface and their tails drooping. If a fish is floating on its side on the surface of the water, it is about to die.
High-quality fresh chilled fish have bright and transparent eyes, protruding eyeballs, tightly closed gill covers, and pink or red gills. They are free of mucus, dirt, and any strange odors. The scales are bright and clean, the body is firm and straight, the belly is full but not bloated, the flesh is firm and elastic, and any indentation from pressing recovers immediately. The anus is sunken. The opposite is true for fish that are not fresh. High-quality frozen fish have a bright color, as vibrant as fresh fish, with a clean body surface and a contracted anus. The eyeballs are full and protruding, with a transparent, clean, and spotless cornea. The body is complete and intact. When cut open for inspection, the flesh is firm and does not separate from the bones, there are no red lines on the back, and the gallbladder is intact and not ruptured. The opposite is true for poor-quality frozen fish.