Do Koi fish breed?
Yes, around 8-12 inches they will tend to breed. The first sign is that your female fish will become large with eggs and the males will start to franticly chase the females around. Koi breed once a year around spring time when the temperature changes. Be careful though, female koi can get badly hurt, or die, from the male koi bashing her on rocks. You should make sure you pond has lots of plants around for the female to lay her eggs in. You can also buy some spawning mats, these mats are layers of soft fibers used to prevent injury.
