How big can koi grow:

1. Common koi, such as red and white koi, cloth koi, etc., can grow to 30 to 40 centimeters.

2. Better quality koi, such as Taisho three-color koi, can grow to about 60 cm.

3. Some top-end koi, such as golden koi, can generally grow to about 100 centimeters.

Factors affecting the growth of koi:

1. Age. Koi's growth peak is before 6.5 years old, but after 10 years old, koi's growth changes very little.

2. Stocking density. The space for koi to swim freely determines its growth. If the stocking density is too high, koi will not be able to swim freely, and the psychological tension and pressure will increase. At the same time, without sufficient exercise, the physical fitness and disease resistance will be reduced. It is greatly reduced, resulting in slow growth of koi and even diseases and other problems.

3. Diet. Koi are very greedy and eat without restraint. They eat as much as they want, and some even stretch themselves to death. Unreasonable diet is particularly harmful to the body of koi.