Actually, koi fish are a kind of carp. Mongrel koi are koi fish that have interbred with different species of fish in some way. In fish ponds, koi fish are well-liked for their vibrant colours and elegant appearance.
Koi are ornamental fish that are kept in ponds to spruce up gardens and outdoor areas. The word “mongrel koi” is used in jest to allude to the general uncertain genealogy of the koi fish; it does not actually have a name.
Koi are only really used as show fish in koi ponds. Multiple fish usually live in koi ponds, which are prized for their beauty. Koi are more expensive than other carp kinds, although their value is purely derived from how pretty they are when swimming in fish ponds.