Japanese Koi Fish

This essay was written in response to enquiries that were received after publication of the article recalling my personal experiences on Koi nutrition in KoiSA # 75.

Society members queried the statements that were made on depth and growth. Thank you for the interest and response. In particular, members asked about the statement - "It may come as a surprise to some collectors, but I have never considered depth to be critical in achieving growth." KoiSA readers have asked me to elaborate on this statement.

One of the claims made in Koi literature and by some South Africans are that ponds have to be deep to achieve good growth in Koi. Further claims were and are regularly still made that Koi keepers cannot grow Koi to a large size in a shallow pond. Please note the two words that have been highlighted.

The first two questions I began asking myself, as I made notes of my observations over the years, were -

1. do all Koi grow to a large size in deep ponds? and

2. do all Koi remain small in shallow ponds?

The answer to both questions is clearly no. If the answer to both questions were yes, this essay would end here. We could then fall into line with so-called world opinion and live happily ever after. The next two questions I started to ask myself were (no, I do not always talk to myself, but thanks for asking)

3. how many large Koi are there in South Africa and

4. how many deep ponds compared to shallow ponds are there?

No matter what we are told or have been led to believe, it is an indisputable fact that many Koi keepers are growing Koi to a large size in shallow ponds. When I observed this fact I tried to find the other factors that must be present that have a far greater influence on growth than pond depth.

The final straw that broke the camels back and turned me away from common consensus was that Koi are not easy to view in deep ponds. It is of concern to me that people can pay a fortune for a fish and hardly ever see it or at the very least see it with difficulty. Rather like an eccentric art collector hiding beautiful works of art in a dark cellar never to be seen again.

Koi are bred specifically to be admired and appreciated. Year's ago I decided I would rather have Koi that were 60cm or 70cm long in a "shallow" pond and see them each and every time I walked past, than a deep pond with possibly slightly larger Koi that were hardly ever seen.

Everyone has a different perception of what a "large" Koi is and what a "deep" pond is. We should therefore, define these two concepts before engaging in debate.

Although we are told Koi can grow to a meter in length there very few Koi of this size or even 90cm in South Africa. The occasional 80 cm Koi is found. There are a very few genuine 70 cm or longer Koi, especially of high quality. Even on the SAKKS National Koi Show very few Koi above 65cm are seen.

When we reach the 60cm - 65cm size bracket we find that most Koi keepers would be happy with Koi of this length. We also discover that no matter what we do and irrespective of pond specifications, the vast majority of Koi simply cannot grow much bigger than this size. Genetics becomes the great leveller of the playing fields and the ultimate limiting factor.

As a matter of interest a summary of 150 top Japanese ponds and pictures of their favourite Koi revealed an average Koi length of about 65 cm. Only the very top collectors had Koi over 70cm that were of high class and finish.