All koi are the same species. (besides cross-breeds like butterfly koi and ghost koi) Koi are classified into different pattern types and the rarest of those would be the Ki Bekko. A koi that is lemon yellow and overlained with sumi (the black splotch pattern), Copy and paste this web address and look at the photo of the Ki Bekko. http://www.koisale.com/koi_bekko.htm
Koi fish Koi fish
Koi fish can live in almost any country. Koi are thought to be originally from Japan. Many people have outdoor fish ponds in which Koi are the dominant fish.
a fish, a koi carp
because it is fish
the rarest fish is the super sized golden trout/salmon cross breed
Koi are a type of specially bred carp.
Nope they sometimes eat there eggs
Koi fish usually have two eyes.
The Japanese for Koi is nishikigoi.
The sex of koi fish cannot be determined unless a)you dissect the koi or b)you witness the breeding.
There is no real data to tell us what the rarest marine fish is. Likely the rarest fish has not yet been discovered, because it is so rare.
Koi fish is suitable as a feeder fish for other larger fish. If a human wanted to eat a Koi fish, (which in general unlikely), it would be better eaten dead.