How Big do Koi Grow? How Fast do Koi Grow?

How Fast do Koi Grow? Improving Growth of Your Koi

It's important to optimise the living conditions and environment and to provide the correct feeding regime. A well designed "proper" koi pond with first class biofiltration systems principally based on the traditional Vortex settling chamber and vortex biofilter units are ideally suited for conditions in which high growth rates can be obtained. These mechanical and bio filtration "plants", for that's what a well designed koi pond vortex filter system really is, have to be well maintained to allow optimum water quality conditions for the koi fish daily living.

Meticulous draining of bio filter systems on a daily basis (maybe more) is required to provide perfect water quality and ideal growth systems.

Even the most perfectly designed koi pond and koi pond equipment will not allow for any koi to grow to its optimum size becasue there are many other factors at play in determining how big and how fast a koi will grow.

In this respect genetics plays a vitally important role and the real world class jumbo koi start life as hand picked fry.

By the way it's impossible to look at a small koi with amazing and magnificent colours and forecast that the same colours and patterns will apply as the fish grows. In fact this is rarely the case which means agonising over the selection of those beautifully marked 4 inch long koi at the dealers can be a complete an d utter waste of time and money.

Koi dealers sell koi fish to the unsophisticated koi buyer by portraying colour and colour distribution along with koi length or mass as major price determining points. The fact is the present (colour and design) is no indication of the future (colour markings and design).

Anyway back to growing koi for the average koi pond keeper and not the koi krazy keepers which is how the koi fraternity do like to see themselves.

a. Genetic make up b. Environment (stocking density, temperature, water quality etc) c. Diet

We cannot influence the genetic make up of the koi in our collection as this is already fixed and determined, so we can only enhance growth by managing either their environment or their diet.

How Fast Do Koi Grow? Keep a Low Stocking Density

• It's simple.. the larger the ratio of pond water mass to koi mass the better will be the conditions for growth. This is described a maintaining a low stocking density. If you think you have too many fish in the pond then you probably have.
• Maintenance of the correct and optimum temperatures year round will significantly improve chances of growing large koi.
• High quality high protein fish foods of 35%+ fed in correct quantities regularly rather than in big single servings will optimise the feeding regime to optimise growth of the koi. This will reduce ammonia "spikes" as they are referred to ... ie an initial and rapid increase in ammonia concentration in the pond water shortly after feeding. So little and often is the rule for correct feeding of koi
• Biofiltration performance must be excellent 24/7 to ensure no knock-backs due to ammonia or nitrite levels being present on an ongoing basis.
• Maintaining an optimum water temperature year round since this determines appetite of fish and ability to metabolise. Temperatures in summer months can be as high as between 25 and 27 degrees C whilst temperatures in winter should be controlled at around a temperature of about 15 to 17. Rapid and sharp swings in temperatures should always be avoided. Like most things in life a degree of stability is important.
• The need for an ultra efficient high capacity koi biofilter is critical. The performance of a biofilter can be dramatically improved by injecting air into the biofilter itself or in the water stream entering the biofilter system. This is one reason why a well designed Vortex filtration system works so well. Air stones are suspended into the upper layers of the vortex unit close to the Japanese matting matrix generally used in these high efficiency well proven koi filter systems. THis intimate mixing of air and water provides ideal conditions for mass transfer to take place and this is the process that drives conversion of ammonia to nitrates.
• Healthy, stress-free fish are fast growing fish. Adequate solids removal and biofiltration are essential to maintain good water chemistry. One significant factor that has been shown to improve growth (as well as biofiltration) is vigorous aeration. Tests have shown that fish convert their diet into fish tissue far more efficiently when dissolved oxygen in the pond is highest.
• There is an optimum rate of feeding fish food but once again the number presented always depend on this that or the other so take them with a pinch of salt. For this reason I have not stipulated any numbers. As an aside these numbers are expressed as a % of body mass of the fish... but how do you know the mass of fish in a pond containing a variety of sizes and shapes?

For me there's a golden rule in koi keeping and it's a rule that applies generally... whenever you're told something which sounds like it's straight from the koi gospel ask why and then test the reply by using a chunk of common sense. My favourite bit of koi bunkum is that a bio filter must be 1/3rd the pond volume.

You know what's important for readers of my articles... it's not the size of the koi or how big the koi will grow. It's much simpler. Are you enjoying your fish and are you learning about ponds and pond keeping for the pure pleasure of it? Let's face it we're not going to set any world records for the biggest koi and who wants to anyway?