Simply Koi and More Koi

Water in Japanese breeders’ mud ponds doesn’t come from springs fed by water that has percolated through the ground, it comes mainly from snow melt or rain water that collects into rivers running off of the mountains and so it has very little contact with minerals in the soil. This means that the pH is low, mainly being in the range of 6.6 to 7.0 in the Niigata and Hiroshima area. Since it contains only small amounts of dissolved minerals, it is also very soft, with the alkalinity in most mud ponds typically being around 14 mg/L (about 0.8°KH) or lower and rarely going higher than 46 to 48 mg/L (approximately 2.5°KH). It is this low mineral content water that is said to have a beneficial effect on colour development and skin quality and there is good reason for this belief.

The cells in the skin that are responsible for its colouration are called chromatophores, and they colour the skin because they contain different colour pigments. The distribution of the pigments within these cells isn’t fixed, they can move. If the pigment spreads evenly throughout the entire cell, it becomes evenly and strongly coloured which means that areas of skin containing these chromatophores are also strongly coloured. If colour pigments are concentrated in one small area within the cell, the cell isn’t fully coloured so the skin colouration looks weak. pH and hardness affect colour pigments differently. Melanin, the black pigment, will spread through the cell to a greater extent in hard water and concentrate in smaller areas when the water is soft. On the other hand, the red pigment, astaxanthin, tends to spread throughout the cell in soft, low pH water, and to concentrate in a small area within the cell where the water is hard. In this way, soft, low pH water favours the development of hi (red) and hard, more alkaline water favours the development of sumi (black).




Of course, water parameters can’t possibly turn a poor quality koi into a good one because colouration is primarily determined by genetics and skillful culling but the appropriate parameters can make a good koi just that little bit better.

Reverse osmosis users are trying to emulate water in Japanese ponds by lowering the “hardness” or GH of their pond water to achieve a balance between water that is soft enough to allow red pigment to spread throughout the chromatophores but isn’t so soft that black pigment contracts within the cells and looks weak.

Using reverse osmosis purifiers to lower the mineral content of pond water can have benefits in terms of colour but it isn’t something that should be undertaken lightly. pH is a very important water parameter and the carbonate hardness parameter (KH) is crucial to maintaining a stable pH. Reducing hardness by reducing the calcium and magnesium content will have benefits but RO purifiers also remove carbonate hardness. The lower the KH, the more likely it is that the pH will become unstable. Biological filters consume great quantities of carbonates and, if they become completely exhausted, the pH will suddenly crash to levels that are lethal to koi.

GH may safely be lowered using reverse osmosis but, to avoid a pH crash, the KH should be regularly monitored and topped up as necessary by adding sodium bicarbonate to prevent it from falling below about 3°KH.

(Hobbyists who don't use RO and who prefer a stable pH that doesn't need to be so constantly monitored are advised to keep their KH nearer to 6°KH).

Nice article and explanations, thank you.

syd

I ran RO water for years my GH was zero my KH was never above 2 and my tds was around 100-120
All my fish came from yume koi apart from one lemon chag, looking back now after I filled that pond in some years ago i never saw good colour or great growth or any real benefit in health so it makes you wonder where all this data comes from? and how much of it is just theory?

dunc

Duncan,

I don't use RO myself so keeping koi in soft water is an area where I rely heavily on the experiences and teachings of breeders. I've only spoken directly to two breeders. One was Saito Masaru from Shintaro Koi Farm when he came over a couple of times to the Newmarket Weekends to talk about koi breeding. The other is Mark from Cuttlebrook. Apart from that, there is Mike Snaden, Alan Coogan et al who visit Japan regularly and talk about the low GH in Japanese mud ponds.

They are all advocates of soft water for good growth and the development of beni so I, (who's only experience of growing on is my motley collection of manky sankes), am in no position to disagree with them.

The diagrams I drew of Chromatophors came from studying koi physiology and is my attempt to reconcile what the breeders say with how koi and other freshwater fish work. There obviously is a lot of anecdotal evidence in what the guys I've mentioned say about soft water but the molecular stuff that goes on in living cells seems to line up with what they say.

If I remember correctly, it's common for Japanese breeders to use masses of oyster shells to increase the GH of the ponds where they keep koi before they ship them to the UK. That helps develop the shiro and prepares the koi for a life in our generally hard water but whether they do this for other markets, I'm not sure so I'll ask, next chance I get.

Manky Sanke wrote:Duncan,

The diagrams I drew of Chromatophors came from studying koi physiology and is my attempt to reconcile what the breeders say with how koi and other freshwater fish work. There obviously is a lot of anecdotal evidence in what the guys I've mentioned say about soft water but the molecular stuff that goes on in living cells seems to line up with what they say.

Syd im not knocking your drawing on the chromatphores far from it, all im saying is there is no hard science behind what soft water does to colour and growth. The Japanese would say soft water is good for this and that, because at the end of the day that's all they have to work with, in their position I would say the same but nobody can point me in the direction of the written word of hard science that's says its fact its all hearsay and Chinese whispers for instance if I wanted to know about ATP or blood conditions in fish I can pick up any number of books that support with hard science any number of events but the same cant be said of colour growth and soft water

without mentioning any names I know many hobbyists that don't do RO or have soft water, in fact have water so hard you could walk on it, yet they grow big fish and have good colour, are they wrong

all I ask and the only thing I ask is some science and reading behind statements like this

dunc

Duncan,

The science behind how chromatophores have various colours or how they can vary their colours is well known and I've found that many times in books and on the Internet but the answer to your specific question about whether hard or soft water can also cause colour variations is, as far as I can tell, the result of empirical observations. There have been several people that I've listened to but the first, and most prolific advocate, that I remember referring to the benefits of soft water was Mike Snaden who wrote a series of magazine articles on the subject.

It was so long ago that I can't remember where I read them all but I recall him regularly talking about "magic water" with low GH which gave good beni, good growth but less well developed sumi and compared that with a high GH which gave good sumi but less well developed beni and poor growth. He even installed a water softener to reduce GH so that he could replicate the results he had seen in Japan. I've listened to a few of his talks since then and he is still passionate about the growth and colour benefits of soft water.

I'm a bit busy with the Poppy Appeal for the next week or so but I'm always making notes and their sources when I find something interesting so, as soon as the appeal is over, I'll dig out my earlier notes and see if there are any references to anything more scientific rather than empirical.

syd

I don't really want to get into this because we are going to go around in circles and end up right back where we started, so I don't see this going anywhere! I know in my heart of hearts given the right genetics I could grow a big koi and retain colour withy higher GH/.KH figures, people like bill Oakley and Ian Stewardson are testament to that

Mike has advocated and written the virtues of soft water for years and wrote many articles as you say, but is very selective in what he writes, omitting stuff that does not fit the model! ( I can think of one such example right now)

as I say I'm done with this because I know as you do its not going to go anywhere and the majority of koi keepers ( no disrespect intended ) are not capable of sailing that close to the wind with KH properties that low! so for 99% of koi keepers its a moot point as you yourself recommend a KH value in the 5-6 range as do I

you and I both know if we recommended right here and now that everybody should run their pond with water parameters as per Japan levels I.E. KH value of 15-20PPM we would have a lot of dead fish in more ways then one, by that I mean, more ways than just a pH crash. The Japanese get away with it because as I say A) its all they have to work with, B) most operate a flow through system so the KH as low as it may be is constantly being propped up

Dunc

P/S im busy building a utility room for polly time is tight at the moment and we have generated 24 views that's all with our debate

It is a good debate guys - and one that I still don't claim to fully understand!

TBH, though I love my koi and the hobby, life is far too busy for me to devote the time I'd need to fully understand all the pro's and cons and, if I did understand it, I doubt I'd have the time to maintain my pond water with a vastly different chemistry to that supplied through my taps.

I am one of those hobbyists who has had to accept that I can only do my best with the water chemistry I have - but that doesn't stop me enjoying the debate!!

Cheers

Duncan,

I have no particular personal opinion on RO, I've listened to some persuasive arguments from a few breeders and from Mike supporting the fact that soft water enhances beni and hard water favours sumi. That was what made me go searching for the mechanism that allows chromatophores to have different colours and how the distribution of pigments affects the colours. If they aren't taking all the facts into account and there is another side to the story perhaps, when you get time, you could give some details. Then readers will have the case, for and against soft water, and they can make their own decisions.

sorry Syd I wrote a reply thought I had saved it in drafts and it was not there when I came back

but basically that's what it all comes back to "What Mike say" its about time some scientific cake was put under all that hear say icing he carps on about, ive been listening to it for years just like the magic properties of bacteria house media, does it sound familiar?

like I say no disrespect im done with this

dunc

Probably not applicable to koi but just my thoughts .


Before koi 8 years ago i kept tropicals on a large scale and was far more into it than i ever will be with koi and still am .

Wild caught discuss as an example needed a low ph of 7 or under , to match where there came from , nothing else would do even if acclimatised to a higher ph slowly they snuffed it .

These very same fish bred on asian farms( iirc ) over a many generations for the aquarium market do very well in a PH of over 8 and even breed .

So i can't see how koi which are man made can,t adjust as such ?

I think that if you select koi on it, they could over generation get shimi spots in hard water a lot better (as in non-existing).
But, they don't select on that in Japan, since they don't have hard water there. If we look at Israel, here they have still a long way to go to produce Hi Quality fish, BUT, they have started selecting fish who,(even) in hard water have good quality (they are forced to since in Israel they have very hard water).

Anyway, we notice that they indeed, in our (hard) water, don't develop shimi spots either.

Generally when rain falls this water is soft water there is only ion is sodium.hard water contain magnessium and calcium.

Thanks for sharing this information. Nice article and explanations, thank you.