Koi Fish

Koi are colored carp. Here is a short explanation about how they came to be from Wikipedia: Koi.

Koi carp were first bred for color in Japan in the 1820s, initially in the town of Ojiya in the Niigata Prefecture on the northeastern coast of Honshu island. The outside world was unaware of the development of color variations in Japanese koi until 1914, when the Niigata koi were exhibited at an annual exposition in Tokyo. From that time, interest in koi spread throughout Japan. From this original handful of koi, all other Nishikigoi varieties were bred, with the exception of the Ogon variety (single-colored, metallic koi) which was developed relatively recently. The hobby of keeping koi eventually spread worldwide. Koi are now sold in many pet aquarium shops, with higher-quality fish available from specialist dealers. The collection of koi throughout the years has become quite the social hobby for many who have ponds. It is also common for hobbyists who are passionate about their koi to join a club specifically for their koi and ponds. Members tend to share their knowledge of the fish with others and even help each other out when they are in need of help with their koi.