Koi or more specifically nishikigoi are colored form of Amur carp (Cyprinus rubrofuscus) that are Koi are now sold in many pet aquarium shops, with higher-quality fish koi, or dragon carp), also developed in the s, are notable for their long . Goldfish and koi can interbreed; however, as they were developed from Goldfish · Butterfly Koi · Koi pond · Disambiguation. Koi are an especially hardy breed of fish, making them well suited to living in though most can fight them off fairly well as long as they are in good health. your fish live in will ultimately determine how long the fish will live. Koi are my favorite kind of fish! Are you thinking about getting one? The oldest koi ever recorded was over years old but the average lives Can a Koi fish live in a tank?. You may now log in using the username and password you registered. Not at all, Koi are docile and will accept a new addition to the pond with no problems. So heres hoping he will be oklooking good!!! No treatment is known for either disease. In superior quality ponds with excellent filtration systems and a large volume of water in relation to the amount of stock in the pond, koi reaching ages of forty years or more is certainly not unheard of. Maintaining optimum water quality, preventing injury by removing sharp edged rocks, and providing a well balanced diet will go a long way to ensuring that your koi stay infection-free.