Not very sough after due to the lack of colour and in many ponds, you won't see him/her. Some would refer to it as a ghost koi.
Part of the Kawarimono group and not a true example of a specific variety.
Might develop into a nice pond fish.
Some people like to have a black fish because they might indicate problems in your pond. (mucus build up due to bacterial problems or white spot can be seen easily which provides an early warning signal and indicates possible problems in your pond)
Some people believe that it is good to have a black fish in your pond because it absorbs all the negative energy towards it and from a Feng Sui point of view, it is considered to bring good luck. I don't believe in most of it but see an article written by my ex on my website at http://www.koionline.co.za/feng_shui.htm
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Koi are not my whole life but make my life whole