Breeding Koi

This article was first written for and published by Koi Magazine in 2007

This article is in fact a Q&A with Mark regarding breeding koi, how he found himself to become a koi breeder and much more. It gives an interesting insight into the farm and the passion that Mark has to make Cuttlebrook Koi Farm the number one UK koi farm.

When did you start experimenting with Koi breeding?

I have never experimented with breeding koi and in fact my first experience was when I worked at Kamihata’s Koi farm in Yamazaki, where on 5th May 1986 I was involved in spawning 20 sets of koi in one night.  At the time Yamazaki was pretty much the largest koi farm in Japan.

What were your first results like?

We started spawning in the UK in 1990 on the site where Cuttlebrook Koi Farm is now with just two spawning tanks.  The idea was to breed in sequence, filling the fry ponds over a period.  We got some good results, for a first attempt, harvesting 10 – 20,000 fry at first cull (around 1 inch in size) per nursery pond.

When did you start breeding on a larger scale?

I can’t say that we have reached the scale of the spawnings at Yamazaki yet, but we now spawn around 10 sets of parents in a season, producing approximately 3 million fry, and harvest between 30 – 75,000 fry at 1 inch (first cull), per nursery pond (usually one spawning per pond).


I have only bred koi for a living, never as a hobby.  I guess I’ve always had a passion for fish, which is why I decided to study fish farming at Sparsholt after leaving school, my other passion in life has always been art.  Nishikigoi are a fusion of my passions, the buzz now is when I create a beautiful living work of art, but as an artist I am never satisfied and am always seeking perfection.

Where do you get your parent stock from?

We source our parent stock from a couple of well respected and experienced dealers in the UK with whom we have a good relationship.  They know the qualities we are looking for in a brood fish and whilst in Japan, they keep an eye out for possible candidates from some of the top breeders.  We also select koi we feel have good potential from their existing stock.

How important is parent stock?

The right parent stock are very important but it is only when you have actually bred with those parents that you can tell if the offspring are of the quality that you are looking for.  The parents that produce the best offspring are often not the most attractive of koi or the most expensive!  When choosing brood stock, we look for certain characteristics in the males and females which will indicate how the offspring might develop.  It is however very much trial and error.

What conditions do you rear your fry in?

Our fry are reared in clay mud ponds that are filled with the nutrient and mineral rich water that we have running in the brook which supplies the water to the farm.  The mud ponds themselves then provide the perfect environment for the natural food, that the young fry eat, to flourish.  After a short period, we supplement this with artificial fry food.

Have you got any top tips for hobbyists?

Don’t try and keep every fry that you produce.  You need to reduce the number you grow in order to give the best ones the best opportunity for growth.  Culling is not always easy to do but it is one of the most critical aspects of breeding nishikigoi.