I've seen them up to 3' and herd stories of them getting bigger. Koi, a variety of carp and closely related to goldfish, tend to grow (or not) to match the dimensions of its habitat. So carp in rice paddies can become quite large, whereas carp or koi in small tanks will remain small.
The size of the koi will depend on many factors such as what type of koi it is, how much and what you feed it and the size of the aquarium or pond you keep it in.
Koi fish Koi fish
The Japanese for Koi is nishikigoi.
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
In Japanese, koi fish is written as "鯉" (koi). The character for "koi" represents the colorful carp fish that are traditionally kept in ponds for their vibrant colors.
because it is fish
Koi are a type of specially bred carp.
Koi fish usually have two eyes.
Nope they sometimes eat there eggs
The kio would be to big. But it would try to attack it. Then they will fight. Dont put bettas with other fish.
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.