The Spring Festival is a day for offering sacrifices to the land gods, usually on a certain day in early February of the lunar calendar (regulations vary from place to place). This time is the time when mackerel lays eggs offshore, which is not only easy to catch, but also the most beautiful.
So "social fish" is "fish that appeared during the Spring Festival".
The living habits of mackerel;
In the natural environment, fish have special colors and stripes, or the body color is consistent with the surrounding environment, so as to hide themselves, or confuse the enemy or prey to protect themselves or sneak attack on prey.
Mackerel living in the middle and upper ocean has a dark back, mostly blue-black, dark blue or dark cyan, and a light belly, which is silvery white, white or yellow-white. This color is called extinction color.
If you look from top to bottom, because the back of the fish is the same color as the sea water under natural light, it is not easy to distinguish even if it is close to the fish. Looking up from the bottom of the fish, the color of the fish's abdomen and water surface is very similar to the color of the sky, which is difficult to distinguish.