Koi are colorful domestic mutations of the common carp and are classified into the same genus and species, Cyprinus carpio. Koi are fast growing and can maintain a maximum length of 38 inches. They grow rapidly reaching up to 7 inches in the first year, though optimal growth is dependent upon temperature and proper nutrition. Koi like cool water a from around 16 to 24 degrees Celsius.
There are 14 color varieties typically recognized throughout most of the world. Nevertheless, there are over 100 color patterns. Not all of these breed true. The recognized varieties are grouped into the non-metallic and the metallic koi.
