The Carp (Koi), the king of the river fish, is much esteemed in Japan for many of its qualities. It is commonly known as an emblem of perseverance, strength, courage and success. These symbolic characteristics are mainly based on the fact that carp are known to be able to swim up a waterfall and up a river over a great distance, even when the flow is very strong. The strength attributed to carp originated in China, where the fish was said to have braved the Wu-Men rapids and to have swum up the Lung-Men falls on the Yellow River.
On May 5, carp banners are flown in Japan by parents and sons to express the hope that their boys will grow strong and healthy. On the banners, the black carp, called magi, represents the father, the red carp, or chigoe, is the mother, and the blue carp, called kogoe, is the child. These colors can be used in tattooing to identify the koi or show the relationship between them.
According to well known legend in japan, carp that swim up Chinas Yellow River and pass through the rapids in Hunan known as the "Dragon Gate" turn into dragons. In Japanese, the idiom "ascending the dragons gate" means "overcoming barriers to success." Images of koi swimming through rough waters symbolize strength and determination. because of this association, koi can be paired with dragons in irezumi tattooing.