1. Mackerel is commonly known as mackerel and bamboo mackerel, and its scientific name is blue-spotted mackerel. Mackerel has a long and narrow body shape, with a blue-black head and back. Most of them are 25-50 cm in length and 300-1000 g in weight. Distributed in the western North Pacific, China is produced in the East China Sea, Yellow Sea and Bohai Sea. The body is long and narrow, with a blue-black head and back. There are several rows of blue-black round spots on the upper side, the belly is white, and there are horn spines behind the dorsal and anal fins. In summer and autumn, they often travel in groups for long-distance migration.

2. In the natural environment, fish have special colors and markings, or the body color is consistent with the surrounding environment, to achieve the purpose of concealing themselves, or to confuse enemies or prey, in order to protect themselves or sneak attack prey. Mackerel fish that live in the middle and upper layers of the ocean have dark backs, mostly blue-black, dark blue or dark cyan, while their abdomens are light, silvery white, white or light yellowish white. This color is called extinction color . If you look from top to bottom, the back of the fish is the same color as the seawater under natural light, so even if you are very close to the fish, it is not easy to distinguish. Looking up from the bottom of the fish body, the color of the fish's belly is very similar to the color of the water surface and the sky, making it difficult to distinguish.