if you look at it that way yes they are from the same family.
but look at it from a koi keepers/breeders side if you keep koi
then you don't have goldfish.
goldfish are something you buy in the pet shop for £2.
koi carp are something you buy off a breeder for £200.
koi won't stand the condition like goldfish do and won't be happy in 2.5 ft of water.
You are seriously deluded. The evidence is clearly produced above, and you still argue against it. You go into a petshop and buy a mature 6" long fish for £2..no it costs £50, even more for Koi. Sure I paid 3-4 quid for the fish origionally, but to buy them now is more expensive. Breeder=petshop.
Goldfish have lived in a bowl for generations, Koi is the same family, what are the reasonings behind that they can't live in 2.5 foot of water, when fish live in a bowl? Living in a pond is their natural habitat?
Koi and Goldfish are Carp, they live in rivers, and ponds. And bowls, that have inches of water, and a circumference of 6 inches, but are unable to live in a pond 3 feet deep? Get real!
Koi ( Nishikigoi) need deeper water for comfort, they are not happy in shallow water at all and it restricts their lifespan and growth. Koi have been bred mainly for their colour and quality, this means that they have lost most of their natural resistance to disease. Goldfish could prob live in a dirty bucket of water and be happy!
Goldfish and Koi belong to the Carp family, but they are totally different fish. I have kept Koi for years and have spent a small fortune on fish and pond set up. The common goldfish is a mutation from the Crucian Carp, Koi are colour bred from the Common Carp. The name 'Koi' actually means Carp.
Goldfish are a very hardy fish and dont need the filtration and care like Koi do, thats why you see them sat in bowls on top of the TV.
The type of Koi you see being sold by breeders would not live for a week in a river, they would catch pretty much every disease out there.
You're right in saying that they come from the same family, but similar fish they certainly are not