They have never studied biology or dealt intensively with the physiology of fish. And yet they know more than many an "expert" in the field of carp/koi! Learning a craft over several generations often replaces "studying" more than anything else, and coincidences often play a role too.
The well-known kujaku koi breeder Yasuaki Kaneko
The father of the renowned Kuyaku koi breeder Yasuaki Kaneko started breeding koi because a customer could not pay cash for his car repair and instead brought him five koi for the work. He diligently learned from the other koi breeders in the Ojiya area and got better and better. Tens of thousands of koi passed through his hands in the selections. He passed on his experience to his son, who now runs the Kaneko Koi Farm. When it came to colouring, father Kaneko tried various foods. From very cheap pellet food from a producer down in the valley, to the most expensive food from a well-known Japanese brand. The most expensive food resulted in better growth and more beautiful colours than the cheap versions. But the colour separation from red to white was still not always as pronounced as he would have liked. Of course he did not know the biological background and had never seen or heard of different forms of carotenes. When the JBL biologists met his son Yasuaki Kaneko, he told them about the colour differentiation problem. An analysis of the food compositions revealed that "normal" carotene was always used to intensify the colours of the koi. This canthaxanthin E161g is produced technically, is inexpensive and is used, for example, for the red colouring of salmon trout. JBL provided Kaneko with a prototype of the JBL PROPOND food range, in which a very expensive astaxanthin E161j was used. This comes from krill and spirulina - so it is always of natural origin.
After just 6-8 weeks Kaneko could see differences in the colouring of his kujakus. The red-white distinction became much better and JBL decided to dispense completely with the cheap canthaxanthin and to use only astaxanthin E161j for the JBL PROPOND range and especially, of course, for the JBL PROPOND COLOR! Thanks to the Kaneko family, whose experience led to the current situation that now everyone can maintain perfectly coloured Koi.
In the mountains of Niigata Prefecture
If you visit the well-known koi breeders in the mountains of Niigata Prefecture, you will notice how they fly the flags of some famous Japanese food manufacturers on their farms. If you think about how much food a koi farm with 500 natural ponds requires, or like the Marusei koi farm with almost 1000 natural ponds, you’ll soon be asking yourself how they can afford it! The Marusei koi farm, for example, requires about 3000 kg of koi food per month. The food referenced on just one of the prettily coloured flags costs a koi enthusiast around €20 per kg. This results in monthly food costs of €60,000. Assuming that Marusei is sponsored and so only pays half of this, it would still be €30,000, which makes about €360,000 per year.
Talking to us in a personal context several breeders said that they mostly only feed cheap food for the masses of juvenile fish, and later change over to expensive food for the koi they select from a size of about 20-30 cm upwards! Should you ever visit the breeders, take a look behind the buildings. There you will see the empty food sacks and you will quickly see how much "expensive" food and how much "cheap" food is really being fed! Who’d have thought it!
More information on the topic can be found in the Themeworld under Fish nutrition .