Carp pronunciation: [jì]; Carassius auratus is an animal of the genus Carassius in the family Carpidae, which is distributed in rivers, lakes, ponds, and other bodies of water in China except for the Tibetan Plateau, and has been introduced to freshwater waters around the world.

The crucian carp is mainly an omnivorous fish that feeds on plants, likes to travel in groups, chooses food and lives, has a plump body, and has a beautiful posture of weaving and swimming in the water. Farmed crucian carp generally have a bulging back, wider body, lighter body color, and silver-white sides; while wild crucian carp have a very obvious fusiform body, smaller head, light yellow body color, and shiny body surface.

The belly is light white and the back is dark gray. Natural enemies from the water above to look down, due to the black fish back and the river bottom silt with the same color, so it is difficult to be found; natural enemies from the water below to look up, due to the white belly and the day color is almost the same, so it is also difficult to be found; often see some articles describing the morning, "the east rose up the fish maw white," this is the reason. Belong to the protective color.