Stocking Densities

Stocking densities have a direct influence on the overall health of your Koi and the quality of the pond environment.

Heavily stocked ponds have a higher chance of disease outbreaks.

Heavily stocked ponds are stressful to Koi.

The higher the stocking densities the faster you have to remove the impurities and the faster the clean water should be returned to the pond.

As Koi grow they take up much more space, consume much more oxygen and add much more ammonia to the system.

Every time a Koi doubles in length it has about 8 times more body mass.

This has severe implications on your pond and filtration system.

8 times the body mass = 8 times more oxygen consumed + 8 times more ammonia added to the pond.

Higher stocking densities run a greater risk of the collection suffocating in the event of the pump being off for some time.

Koi length 1    

  Koi lenght 2

Decision Time

After a year or two, if your Koi have doubled in length, it may be decision time –


  Koi Lenght 3

Koi Length to Mass Ratio

 Koi Lenght 4


  • The larger the mass of a Koi, the greater the oxygen consumption, the greater the amount of ammonia excreted into the water.
  • Weight increases disproportionably with body length.
  • A doubling in body length does not produce a doubling in mass.
  • Note the 7 - 8 fold mass increase as the length doubles from 20cm to 40cm.
  • Each Koi can double in length in about two years. This would mean a 7 - 8 fold increase in the load on the biofilter and the oxygen demand. - plan ahead -


The Effects of Koi Growth on the Pond System

  Koi Lenght 5

Would you have originally stocked your pond with 640 x 10 cm Koi?