This Interview was conducted in June 2013 and first appeared in Issue 1 of Nishikigoi Digest International

Jumbo Kohaku, Bred by Dainichi Koi Farm, 90bu Kokugyo Prize 2014 All Japan Koi Show, 85bu Kokugyo Prize 2013 All Japan Koi Show, Grand Champion 2012 Niigata Nogyosai

Jumbo Kohaku, Bred by Dainichi Koi Farm, 90bu Kokugyo Prize 2014 All Japan Koi Show, 85bu Kokugyo Prize 2013 All Japan Koi Show, Grand Champion 2012 Niigata Nogyosai

NDI – Mike, first of all can you tell us how you got interested in Koi in the first place?

Mike – I’ve always been interested in fish in general, including Koi really since I was a child.  The first time I had fish I was about 11 years old, my stepmother had a whole load of goldfish in a 4ft tank and there was just 1 white Koi in there.   That Koi nicknamed ‘McAlpine’ because it used to move and shift all the gravel around the tank like an excavator would. Basically I took to looking after the tank, cleaning it out and buying new fish for it, that kind of thing.

When I was around 13 or 14 was the first time that I saw Koi at a Koi outlet, that was a place called Blagdon Water Gardens, and I was amazed at the time because there were a load of Yamabuki Ogons, one pond with only Yamabukis in, which I assume were around 2 or 3 years old, they were £200 each and around 18” long.   I was completely blown away by the fish at the time and just thought ‘wow these things are really expensive, this must be just a rich man’s hobby’ and never for one minute imagined I’d end up keeping Koi let alone deal in them.

When I got married in 1993 my wife and I went to Jersey on our honeymoon and that was when my wife saw Koi for the first time and basically after spending time becoming intrigued by them and throwing them food turned around and said, ‘maybe we should have a pond at home to keep Koi’, and the rest is history because literally as soon as we got back we started straight away with digging a pond and that year, 1993, it was up and running and that was it.

NDI – Moving on much nearer the present day; your main interest, something you write and talk about extensively, is your passion for growing small fish into big fish.


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Mike – Yes, for me that’s just something which is incredibly challenging in so many ways.  It’s challenging to get fish with the right kind of genetics, and then to find ones with the right kind of body type and qualities, to do that in itself is something which is extremely challenging but then to actually grow them as well and get those fish jumbo is actually so rewarding, but there are so many pitfalls in trying to raise fish that the only way really that you can learn with the whole thing is by your mistakes and that’s really what makes it so difficult, so challenging and yet so rewarding when something actually does grow up well.

NDI – obviously genetics are the main thing, if the genetics aren’t right to start with then you are never going to actually achieve anything, but even with the right genetics it’s easy to make things go wrong and there are many other factors involved in that  such as the pond, water quality, feeding, temperature, all those kind of things.  Of those things which do you consider the most important?

Mike – Really the most important thing is the genetics and bloodlines because what I’ve found really is that you’ve got to kind of look at a breeder’s business model  before you decide whether they’ve got the right kind of fish for you because at the end of the day if the breeder is focused on just producing attractive Koi for export, or whether they are producing Koi that they want to try and win smaller prizes with at the All Japan Show, you’ve got to use that to make a judgement call on whether they are the right fish for you.  So at the end of the day I think that if you are going to buy Koi that are going to become big jumbo Koi you need to make absolutely sure that that breeder is consistently raising large numbers of those fish jumbo that he’s actually bred because at the end of the day if you’re not seeing fish of 85 or 90cm+ from that breeder that you’re considering buying from the chances are you’re not seeing them because they are not capable of getting to that size.

NDI – just picking up on the use of the word ‘jumbo’, a word we hear thrown around all the time now from jumbo tosai through to jumbo nisai through to jumbo Koi, what is your definition of a jumbo Koi when you say you are trying to achieve jumbo size.

Mike – to me anything 85cm+ is jumbo, I mean 80cm+ is big, but 85cm+ is a whole lot more challenging in itself so really I think you’ve got to pass that 85cm magic marker as it were and then you can call it jumbo, but nowadays we are seeing more and more fish growing 90cm+ assuming the lineages and genetics are right so that benchmark, if you like, of the word jumbo is getting pushed forwards all the time.

NDI – OK, so assuming we’ve found a tosai or a nisai with the right genetics, now looking at the environment we are going to keep the Koi in, what are the key things for providing the correct environment for that fish?


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Mike – there are so many things, it’s unlike any other animal that you can consider in so far that you’ve got water chemistry, filtration, you’ve got pond water depths, turnover rates, heating regimes, feeding regimes there is just so much to consider with it but at the end of the day you have to consider the pond to be an eco-system in its own right, you can’t just think about ammonia and nitrite levels,  or ammonia, nitrite and nitrate and pH, you’ve got to look at so many other things in order to actually conclude that that system is actually fit for raising fish in in the way that you intend to.

With regards to pond depth I think too many people build ponds that are too deep, for example a pond like in the old days that was 2m deep is just too deep and causes too many problems. I think 1.5m deep is an ample depth for any pond and ponds over 1.5m deep cause more problems with growing Koi jumbo than ponds that are lesser or with depths of 1.5m.

NDI – can you give us an idea of some of those problems that are caused by having a pond of 2m or deeper?

Mike – It’s a very long story in so far as basically it would seem that deeper ponds tend to cause a lot of swim bladder issues.

I think what it basically boils down to is that if a pond is 2m deep it’s very easy to put too much aeration in which results in water that becomes too high in dissolved oxygen saturation, it’s quite easy to go past 100%, which in itself is fine but of course what is probably going to go hand in hand with that, and it’s hard to actually quantify, is nitrogen gas levels and basically total gases are also going to be over saturated if you are saturating the oxygen to that level so easily.

What I’ve found is that if you run a pond of say 1.5m deep you can put a lot of aeration in there and yet still run 85-90% O2 saturation and yet you can have just 1 air stone in there and still hit the same level of 85% plus whereas in a 2m or 2.2m deep pond if you were to run one airstone, even only a couple of feet down (60cm), it’s actually quite easy to go beyond 100% O2 saturation with hardly any aeration.  Another side effect of this I think, in particularly deep ponds,   perhaps 2.5-3m deep and you are running a lot of aeration in there,  it’s quite easy in theory to run 110 or 120% O2 saturation and that in itself causes problems because what happens if you have a power failure, or any kind of problem, the fish have become very reliant on those levels of O2 saturation so even a very short power cut you can end up with an O2 level of perhaps 90% or something like that which is ample in normal circumstances but with fish that have become accustomed to the higher level they just can’t cope with it and dies very easily.


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Also, another thing seems to be the case is that if you medicate ponds the O2 saturation drops as it normally would because of the oxygen being ‘consumed’ by the chemicals and I think it’s a lot easier to kill fish in a deeper pond by medicating even if you’ve got a lot of aeration in the pond it pulls the O2 levels down to a level that the fish basically can’t survive in no matter how much air you’ve got in there.  I think that when you’ve got a shallower pond the O2 saturation is lower, the gills are redder as a result of it and consequently in the event of a power failure you can go maybe 5-6 hours without the fish even showing any signs of gasping and things like that.  I think it makes things a whole lot simpler in so many ways.

Another thing to consider is an issue with swim bladders with deeper ponds.  It seems that in heavily aerated ponds that are say 2m deep or more a lot of fish that are on their road to being grown jumbo, when they get past 75cm will quite often start to come up and gulp at the surface and then go down and blow bubbles through the gills.  If that carries on in a prolonged manner for any length of time you end with a Koi sat on the bottom with swim bladder problems.  You don’t tend to see any swim bladder issues in shallower ponds, ponds of 1.5m depth tend to cause very few problems with swim bladder issues whereas ponds with 2m depth I’ve seen personally as a dealer a lot of high end customers, hobbyists that have been keeping real high level fish, growing them jumbo, and the amount of failures they’ve had to do with swim bladders is just unbelievable.   The more common factor between all of those hobbyists is inevitably if they are buying high end fish chances are that they have a high end system to keep them in and consequently those ponds tend to be quite deep as, if you like, a financial side effect of having of having the money to build a big pond.

NDI – OK, so if we are saying 1.5m is considered as being an optimum depth, in terms of total volume of water for someone wishing to grow Koi to jumbo size what would you be suggesting as a minimum, or for example do you consider the length is more important in terms of swimming distance?

Mike – I don’t really regard any great importance or significance of having a pond of a certain size.

Personally I would always advise, if growing Koi to jumbo, Koi have a sense of safety in numbers so it’s important to have a pond of a size where you can have enough Koi in there so they feel comfortable, so for that argument I would say 30 tons as a baseline for a decent sized pond.  Upwards of 30 tons is a good size, you can stock it reasonably well, the fish will be happy, they’ll be confident, but of course you don’t need that because at the end of the day although that might be something that’s the ideal environment.

I wouldn’t dissuade somebody from trying to grow Koi jumbo in a pond that’s say 10 tons, I think at the end of the day it doesn’t really come down to how big the pond is or how long it is or that kind of thing what it really comes down to is water manipulation.


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What I mean by this is that if you’ve got a pond of say 10,000 gallons, or to make it easy let’s say a 40ton pond, and you turn that pond over 100% per hour, and change 10% of the 40 tons per day, just hypothetically speaking, and then if you took all the filtration off of that pond, and put it and the Koi in say a 10ton pond, you can actually make the 10ton pond behave like the 40ton pond just by turning the water over at the 40ton per hour flow rate and doing the same water changes as if it were a 40 ton pond, you can make the pond therefore behave really, water chemistry wise, as though it was a bigger volume of water so I think it’s really quite easy to cheat the system if you want to try and grow Koi big.

NDI – If for example a pond is only 10 tons is there not a concern about there not being enough swimming space for the Koi to develop its body shape and mass through lack of swimming distance?  

Mike – not really, I think that’s kind of used as a poor excuse really.

In days of old dealers have always said to people ‘oh yeah, you need a pond of 2m deep or more’, whereas in reality, although they say that’s to do with making better water pressure on body and making a better body I don’t think it’s really relevant at all, I think in actual fact if the fish you are buying has got the right kind of body type then the fish will grow up with the right kind of body type, it doesn’t need deep water to do so and I think a dealer that says, ‘that fish hasn’t worked out well because your pond’s not deep enough and that’s why it’s got too fat’, it’s not a problem with the pond at all, it’s the fact that the dealer concerned was buying fish in the first place with the wrong kind of body type and that’s the issue.

To illustrate that we have a gentleman over in Wales whose got a pond of 1450 gallons, it’s round, it has a statue in the middle, and is 90cm deep.  The gentleman’s got 8 fish in there, they’re all Kohaku, several of them are around the 80cm mark or just over.  One of the fish he grew last summer, it was quite an old fish, he bought it as a 4 year old at 60cm, but he grew that fish to just  shy of 91cm and the body type on the fish was absolutely perfect. To me that’s pretty good evidence of the fact that water pressure and exercise doesn’t really have much bearing on the body type of the fish.  I think also big fish tend to be very lazy in their general day to day habits, they swim around quite slowly, and they don’t really need exercise, big fish don’t really want the exercise either, I think they are uncomfortable being pushed around by strong currents and heavy aeration, that kind of thing.

1450 gallon pond Mike refers to in the article

1450 gallon pond Mike refers to in the article

Koi in the 1450 gallon pond

Koi in the 1450 gallon pond

Old picture of the 1450 gallon pond

Old picture of the 1450 gallon pond

The Kohaku above was grown from a 53cm nisai to a 71cm sansai in the 1450 gallon pond

The Kohaku above was grown from a 53cm nisai to a 71cm sansai in the 1450 gallon pond

NDI – for a number of years now you’ve been a strong advocate of reverse osmosis water


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Mike – I am very much of fan of it. Really, anybody can grow fish at a relatively fast rate, but I think you need some kind of benchmark to put towards what you would call fast.  What I mean by this is that in reality if you are growing Koi in your own pond you should be able to at least match what the breeders are doing in Japan with their mud ponds and I think this is important.  If you want to raise Koi jumbo you’ve got to look at the typical sizes the breeder would obtain with his fish.  So, let’s say you buy a breeder’s tosai at 35cm, and yet as nisai they make 55cm, and then sansai they make 65cm, yonsai 75cm and so on, you need to be sure that if you’re on track with raising those fish you should be hitting the same sort of sizes, and I think it’s actually very easy to better those growth rates.

Mike's RO system

Mike’s RO system

But, what you also need to look at is how you are actually doing it because at the end of the day, to my mind, if you’re making a good pond that’s a good eco-system you should be able to raise fish with 5 or 6 months of summer with no winter feeding whatsoever, just purely summer growing, and temperatures of 23/24°C. However, I think if you are in a scenario whereby your water is no good, or you’ve got hard water or something like that, then in some respects you’ve got no alternative but to heat your water hotter for longer times of the year and feed heavier, the problem is if you do that the fish will grow up and look a lot older than they really are compared to those that are raised in better water with a shorter summer growing season.

Reverse Osmosis I think is particularly good because at the end of the day what you’ve got to consider is that Koi aren’t carp, they aren’t things that have been raised in Europe and genetically adapted to Europe, these things have been genetically adapted if you like over centuries, or generations, should I say, to have been raised in Japan in mud ponds with effectively very low pH levels, very low organic levels in the pond, even though they look dirty that doesn’t necessarily mean they are organically loaded as such, but very low TDS water that’s very very clean really and this is kind of what they are genetically used to.

To my mind you’ve got to try and replicate that and replicating it with RO is I think your best option.  You can grow small fish relatively quickly, say tosai through to nisai, with hard water but what will happen is that the bottleneck is really when the fish get bigger, they become a lot harder to grow and that’s really where reverse osmosis makes things a whole lot easier. I also think that if you’re raising any kind of Koi it’s also better to run with a lower pH of say between 7 and 7.5 and that can be very hard to do in a concrete filtered pond without resorting to RO and that’s where it becomes really useful because firstly you can use it to run the lower pH level, which is a lot better for the fish anyway, it keeps the colour more youthful, you get better growth, but also using RO later on in life when the fish are bigger kind of prevents that bottleneck where the fish stop growing so you can carry on going with them.

NDI – in terms of specific numbers of what you are achieving with RO, what is it you are aiming to run ponds at?

Mike – what I’d like to do and what I succeed in doing are two different things.  What I would like to do is to run each pond at a TDS of around 100ppm.  Obviously that figure means very little unless you know the baseline of the water that’s going into the pond because at the end of the day you could have water in the pond that has 200ppm TDS but it doesn’t really mean a lot because if your supply water is coming out of the tap with a TDS of 70ppm it’s effectively telling you that you’ve got 130ppm of organic by products that have built up in the pond over the years and is actually a sign of really poor maintenance, whereas likewise you could have a pond with TDS of 200ppm and mains water, which may be less than ideal, but coming in at say 180ppm the 20ppm differential indicating that you are actually looking after the pond really well.


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Mike's TDS tester

Mike’s TDS tester

But, with all things considered what I would like to do is have a good enough supply of RO water and be able to mix water with it to keep the TDS of around 100ppm, I think in that situation it’s really easy to grow fish quickly and big and keep them looking youthful, and also keep them having quite a nice appearance.  I think if it’s too soft maybe the colour is not so attractive.  At 100ppm you can have the growth and the colour looking good for taking fish to shows as well.  Personally I find that a lot of the water that we’ve got here, by the time we get to the end of summer we are up around the 150-160ppm mark which is not so good, it still works OK but it’s not exactly where I’d like it to be.

NDI – So the reason for that being higher at the end of the summer is just because you are growing and feeding through the summer?

Mike – Yes, that’s it, it’s a heavy loading on the pond, heavy feeding and really not enough water being changed in relation to how that pond’s being run so that causes the slow rise through the course of the summer, particularly really through August and September because that’s when I feed a lot heavier and I think that those are the 2 months whereby I think it’s best for actually feeding fish to get most of your summer’s growth, August, September and rolling into October.

This Kohaku arrived as nisai. Owned by an overseas customer she resides at Yume Koi. Sized 83cm she won Mature Champion at the 2013 BKKS National Koi Show.

This Kohaku arrived as nisai. Owned by an overseas customer she resides at Yume Koi. Sized 83cm she won Mature Champion at the 2013 BKKS National Koi Show.

This Sanke arrived as nisai and now measures 78cm as yonsai. Despite being male, Mike hopes to grow this Koi beyond 90cm.

This Sanke arrived as nisai and now measures 78cm as yonsai. Despite being male, Mike hopes to grow this Koi beyond 90cm.

Originally purchased as tosai, this Kohaku was grown to 78cm by the time it was gosai.

Originally purchased as tosai, this Kohaku was grown to 78cm by the time it was gosai.

 

Continues in part 2 – http://nishikigoi.life/2014/08/27/growing-jumbo-koi-theory-and-practice-interview-with-mike-snaden-part-2/


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