Koi fish tattoos are traditional tattoos symbolizing good luck in the Japanese culture. The idea behind this belief comes from the natural perseverance of the actual koi fish in nature. The koi fish must swim many miles upstream to spawn and continue its species.
Japanese legend surrounding the koi says that if one of these mythic fish succeeds in traversing both the upstream voyage of the river, and in climbing the falls of the Dragon Gate on the Yellow River, it will then magically transform into a dragon. So not only are koi fish tattoos a symbol of luck, they are a symbol of ambition in the face of adversity, success, and advancement in life.