Koi Growth Rate - Facts and Details

If one wants to keep Koi in their home pond as a relaxing hobby, it is necessary to know if the allotted pond space will be suitable for the fish throughout its complete growth cycle. As a proper living space and habitat are essential for healthy Koi, an enthusiastic hobbyist would do well to do some research about the actual growth rate of their Koi.

Koi, the beautiful fish species, is an indiscriminate grower, which outlines that it grows throughout its life cycle. Like humans, they exhibit a rapid growth pace in the initial years of their life.

The average growth of Koi is 80 centimeters, which is around 31.5 inches, while some have been noted to grow to a length of 100 centimeters and 39.37 inches or 3.28 feet. As a newly hatched Koi only measures about 1/16th of an inch, the rapid growth rate of the species is evident from the average size it acquires over the course of its life.

According to the growth equations of Ludwig von Bertalanffy, it can be estimated that Koi reaches about 50% of its complete adult length in 24 months. It achieves a level of 95% growth in 10 years and reaches its maximum length that is 99% growth, in a matter of 14 years.

Depending upon the age of the fish and the assurance of a healthy and optimum living habitat, Koi fish have been noted to grow at a rate of around 2 centimeters per month or more!

A newly hatched Koi weighs a few milligrams and acquires a size of 18 kilograms or 40 pounds within a period of 10 years, which is an estimated increase of 360,000 times within the period, proving testimony to the rapid growth cycle of the species.

The typical growth rate cycles of Koi have displayed the following trend:


Estimated Growth In Inches


8 inches


12 to 14 inches


16 to 22 inches


24 to 28 inches

Ongoing years

1 to 3 inches growth


These growth rates are essential for every aspiring Koi keeper thinking of breeding the pretty fish in their pond.