Giant Wind Koi - Koinobori Black

The big black (magoi) represents the father.
According to a Japanese children's song, the red the first-born son is, in modern Japan it is rather seen as representation of the mother.
The smaller (normally green and blue) represent the other sons of the family.
Whenever a son is born a new Windkoi is hung up.
The black Koi is the largest. In a normal family set it is about 1.5 m long. However, it may also have up to 10 m in length.
These are often suspended on large buildings or bridges.
The smaller ones are sold as toys or souvenirs. Traditionally, the grandparents pass a set of Windkois to the parents after the birth of the first son.
The Koi has become a symbol of health and is often used as a design motif.