Koi (鯉) or more particularly nishikigoi (錦鯉, actually "brocaded carp"), are ornamental ranges of domesticated typical carp (Cyprinus carpio) that are kept for decorative purposes in outside koi ponds or water gardens.
Koi ranges are identified by pigmentation, patterning, and scalation. Some of the major colors are white, black, red, yellow, blue, and cream. While the possible colors are virtually limitless, breeders have identified and called a variety of particular classifications. The most notable classification is Gosanke, which is comprised of the Kohaku, Taisho Sanshoku, and Showa Sanshoku ranges.
New koi ranges are still being actively developed. Ghost koi established in the 1980s have become incredibly popular in the United Kingdom; they are a hybrid of wild carp and Ogon koi, and are identified by their metal scales. Butterfly koi (also referred to as longfin koi, or dragon carp), also developed in the 1980s, are notable for their long and running fins.
In Chinese viewpoint, yin and yang (also yin-yang or yin yang, 陰陽 yīnyáng "dark-- bright") describe how relatively opposite or contrary forces might actually be complementary, interconnected, and interdependent in the natural world, and how they may give rise to each other as they relate to one another. Many tangible dualities are considered physical symptoms of the duality represented by yin and yang.