Some Koi can get to be a meter long which is 100 centimeters, 3.28 feet or 39.37
inches.

Obviously their size depends on the environmental conditions such as pond
size, oxygen concentration, water
temperatures, water quality, amount and type of food. Vitamins and exercise may
also play an important role.

In the mid 1980's in Lake Biwa in Japan they netted a 6.5 foot Cyprinus
carpio, but it died in a public aquarium in Kyushu. There are other examples of
carp reaching enormous sizes in large bodies of water.

It appears that depending on their age and under optimum conditions Koi can grow over 2
centimeters (almost an inch) per month or faster, remember there are 2.54 cm in an inch. Check out the
growth rates in the following graphs.

Just click on the charts to expand them - then click on your browser's back arrow to
return.

Graph A shows length in cm versus age
in months.

Graph B shows length of Koi divided by
age which is a rough gauge of growth rate.

Graph C is of an empirical equation that shows length in centimeters and inches versus age
in months.

Graph D is the 1st derivative of the above equation (Graph C) which is another measure of
the rate of growth versus age. It is only as accurate as the above equation which although
questionable can be improved with more data.

The true rate of growth in centimeters per month as a function of the Koi's age is
probably somewhere between Graphs B & D, both of which show fish need to be fed well
particularly during their prime growth period, when under 2 years of age.

We would appreciate any comments and age versus length data you can send us to make
these graphs more accurate.