Koi or Nishikigoi are the descendants of carp fish. Carp were found in Central Europe and East Asia, they were mainly domesticated in East Asia and used as a staple food source to survive in severe winter weather conditions. Dating back as far as 200 years to Niigata city in Japan, the farmers breeding carps for food found peculiar color mutations in the carps which were vibrant and started selectively breeding them producing varieties of Koi. https://www.grandkoi.in/things-to-know-before-buying-koi-fish/