This is the 2nd part of this interview which was conducted in June 2013 and was originally published in issue 2 of Nishikigoi Digest International.

Part 1 can be read here – http://nishikigoi.life/2014/08/27/growing-jumbo-koi-theory-and-practice-interview-with-mike-snaden-part-1/

NDI – We touched on water temperature a little  earlier.  Can you give us an idea of what you consider your ideal temperature regime would be?

Mike – I don’t think there is any point trying to heat the Koi to any kind of temperature in winter, and there’s certainly no point in feeding the fish in winter, unless you’re at 19 degrees or more the fish aren’t going to grow anyway.  However, if you keep the water temperature during winter months at say 15 degrees the fish will lose quite significant weight.

Most breeders tend to keep their fish at 12°C in the winter months, literally from the time they are harvested at the end of October or beginning of November through until the following April, and they’ll keep those fish indoors and they won’t feed the fish at all.  At 12°C sure the fish will lose a little bit of body weight but they won’t lose any significant amount of body weight so it’s quite easy for them to put it back on again.

You can go lower in winter, you can drop it down to maybe 7-8°C no problem at all but I think if you are going to go that low you need to know that the fish are in extremely good shape health wise and parasite wise before you drop it that low.


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As far as summer temperatures go what I usually try and recommend doing is to get up to let’s say 20 degrees, something like that, by May time and then if by the end of June you were up around 22-23°C start feeding a summer growth type of amount of food if you like but it’s important I think not to overfeed the fish early in the summer because I think if you feed them too much too early all the fish do is make eggs and get fat and the problem with that is that when you get through into the main growth months, which is really August onwards, if the fish are too fat in those months then you find yourself not actually feeding as much as the fish really could be utilising for growth because you are worried about them being too fat.  So, I think it’s better to go very very steady through that first part of summer with that 23 degrees and then August onwards you can literally pretty much double the amount of food you feed them and really start getting serious growth out of the fish, I think that’s a much better regime. I think really your optimum summer growth temperature is going to be 23-24°C, some people heat higher than that but I think the problem you’ve got with that is that with big fish, the metabolism with those is such that if you start heating them to say 26 or 27°C the fish have a much lower appetite, basically because their gills aren’t so efficient at getting the oxygen out of the water and the oxygen levels are lower, so effectively the fishes growth metabolism goes up so they grow faster if you like but they won’t eat so much food so if the water is too hot the growth is too fast and the fish don’t eat enough food so consequently you can’t get the body on the fish, so I think 23 or 24°C is really where you’d want to be.

NDI – Lots of people that read this interview won’t have the same climate as in the UK, for example people in countries such as the Philippines, Indonesia and Malaysia.  This may be a difficult question for you to answer simply because you’ve no experience of doing it, for the people in those countries where daily temperatures of 30°C are normal, if you were them would you still be trying to manage the temperatures as you’ve explained above?

Mike – I would but the trouble is, like you say Mark, some of those countries don’t really have a winter so I think it can be difficult to raise fish and keep them big and youthful, it’s feasible but it’s just difficult. What I know some hobbyists are doing, certainly in Indonesia and I would imagine other places as well, is putting chiller units on their ponds to cool the temperature down but I think perhaps you’ve got to be a relatively wealthy Koi keeper to be keeping fish in that manner because I don’t think those units are cheap to buy, or to run, so it’s kind of difficult.  I don’t really envy people in hot countries, as much as our climate is not great and it costs a lot to heat the fish at the end of the day it’s easy for us to choose what the fish temperatures are going to be whereas in some of these other countries there’s not an awful lot they can do about it.

Indonesian pond which utilises large air conditioning units to cool the water

Indonesian pond which utilises large air conditioning units to cool the water

Indonesian pond which utilises large air conditioning units to cool the water

Indonesian pond which utilises large air conditioning units to cool the water

NDI – Again something we touched on briefly earlier, feeding.  Your main feeding period starts in May after a period of fasting?

Mike – Yes, towards the end of May is when I start feeding.

NDI – And what sort of percentages are you talking about when you start feeding and what kind of food are you using?


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Mike – I’ve never actually calculated and done it on body weight but 2% of bodyweight per day is the norm.  With young Koi such as tosai it’s possible to use a little more than that, perhaps 2.5%, and with jumbo Koi they are a lot lazier in their eating habits so with bigger fish you’d be looking more like 1.5% of bodyweight per day.  What I tend to do personally is feed the fish with a general kind of feel for what I’ve fed in previous years with a rate that I think is about just right and then just observe the fish week on week and if I think they are putting on too much weight then I ease off on the food and if I think they’re not carrying enough weight then I increase the amount of food that I’m giving.  It’s not a scientific way of doing it but it seems to work reasonably well for me. I think it’s quite easy to a degree to overfeed fish, particularly young fish, so in that regard it’s probably better to stick to the 2% or 2.5% daily feed rates because what you’ll find, if you actually overfeed small fish, or any fish for that matter, obviously they get too fat, that’s one problem, but it’s quite easy to raise young fish and overfeed them on a daily basis.  When you first get them they eat a lot but what happens is that if you’re overfeeding after a few days they start to eat a lot less and then you find yourself thinking the fish are fussy eaters and they’re just not eating enough whereas in reality you just trying to overfeed them and that’s why uneaten food is floating around all the time.

NDI – A question I often get asked is ‘what food do the breeders feed?’ I know there is no definitive answer to that, breeders will use lots of different types of food depending on the type of Koi, and brand preference.  For you personally what food are you using as a general rule?

Mike –   Lately I’ve been using FD food.  I think ultimately I would like to be using Saki Hikari but it’s the same scenario as it is for a lot of breeders, they’d also like to feed Saki Hikari to everything but they can’t really afford to so it’s kind of a tricky one.

Personally I think most Japanese foods are actually pretty good, the ones that are actually made in Japan.  I don’t think that you can go far wrong with those because the Japanese manufacturers are not just giving food out to a bunch of hobbyists to get on with it and then putting the food into production. What the Japanese companies are doing, and I’m sure you’re aware of this yourself Mark, is to sell the food to a certain breeder who will trial it for quite a while and during the course of that the breeder will report back to the food company and say ‘well OK, the fish are doing OK with this’, or perhaps they’ll say, ‘my fish are getting too fat with it’, or ‘the body types too weak in the tail tube’.  Various different things they’ll report back with and the food companies will try to continually keep on tweaking and adjusting the recipe until the breeder’s happy with it.  Because of that I think the food companies in Japan have got a whole lot more understanding than companies outside of Japan that basically manufacture something that they think is a pretty close replica of a food that they regard as being good but in reality the problem being is that you might find your fish in the first year you feed it are fine, and maybe in the 2nd year you think they are fine as well, but when you are trying to grow this fish through to jumbo you might end up with a fish that effectively, after 6 years of feeding with that certain brand of food the body type is actually not too good and you might even find yourself looking at the fish and thinking ‘well it’s too fat, the tail tube’s too weak’ or whatever and maybe the fish was no good to start, but in reality the food that you’ve raised that fish on tirelessly for 6 years is actually no good.  So, personally I think, for me it’s just got to be Japanese foods.

Mike Snaden's Koi feeding, on this occasion they were being fed with FD Foods pellets

Mike Snaden’s Koi feeding, on this occasion they were being fed with FD Foods pellets

Mike Snaden's Koi feeding, on this occasion they were being fed with FD Foods pellets

Mike Snaden’s Koi feeding, on this occasion they were being fed with FD Foods pellets

Mike Snaden's Koi feeding, on this occasion they were being fed with FD Foods pellets

Mike Snaden’s Koi feeding, on this occasion they were being fed with FD Foods pellets

NDI – OK, with regards to the specific type of food, are you feeding a growth food, colour food, a mix, wheatgerm, what do you prefer?

Mike – I don’t like too high protein. I think high protein food is OK for young Koi like fry or tosai. I think young fry can utilise much higher protein levels than older fish can.  For me I think somewhere from 35 through to 40% is about right for generally raising fish and with those kind of protein levels it’s easier to feed the fish and get it right as it were. I think if the protein is too high you end up with some fish that will grow quite easy and some fish will just get too fat too easily. I think it’s hard to control what goes on with the whole pond environment with a food that is too high in protein.


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I tend to use a fishmeal base food with some colour ingredient in there, or a certain amount of colour food mixed in it, and I think for me that’s about right.  I’m not really interested in wheatgerm food but that’s really just my preference, at the end of the day I think that fish need to be fed very much on a fish meal based food.

NDI – Lots of people consider wheatgerm food as the starter food for the season for example. Is that something you agree with or perhaps just a marketing ploy or a bit of a fallacy?

Mike – I think it’s very easy for fish to digest wheatgerm food so I think yes, starting off in the early part of spring or summer it’s not a bad thing as it’s easy for the fish to deal with it and utilise that food but I wouldn’t personally be inclined to feed it beyond that.  What I do think it’s good for is conditioning fish for shows because at the end of the day you’ll find that using very low protein food, or wheatgerm food, you’ll get much better skin condition on the fish. So, if you’re trying to prepare fish for Koi shows in that instance I think  that wheatgerm food is quite a good move because it will allow the skin, particularly the skin on the face of the fish, to brighten up a lot compared to higher protein food which, let’s face it, when you’re feeding fish through the summer months quite heavily the skin of the fish can go out of condition really easily, it’s quite common to see fish that are kind of quite yellowy skinned or very muddy skinned. Personally I don’t think that’s a problem because it’s something that’s quite easy to address.  If you’ve got a Koi show coming up, or likewise going into winter, you can stop feeding  those fish and because there’s no real loading on the kidneys or anything the fish actually brightens up, effectively the fish is kind of in detox mode when you stop feeding it.

NDI – We spoke at the beginning about pond systems, pond size and depth.  In terms of the full system can you explain your ideal system in terms of filtration etc?

Mike – You’ve got to firstly start with the footprint that you’ve got available.  Let’s just say for argument’s sake you’ve looked at your garden and you’ve worked out you can get a 30ton pond in there.  Then you have to look at the the pond, say OK, the pond is going to be 30tons, stick to, as we’ve talked about before, the 1.5m depth as a maximum. Ideally I would say 1.3 or 1.5m is where you want to be but, assuming you’ve got that pond of 30tons, what you’ve then got to look at is turnover rate and dynamics of the pond.

What I would say is that if you’ve got a 30 ton pond, or whatever pond you build, I really think you need to turn the pond over every hour in order to make good water, I don’t mean good parameters, I mean water that’s a really good eco-system for the pond,  that’s very much alive with bacteria. So, with that in mind, if you just said OK then the pond’s 30 ton it’s going to be turned over at 30,000 litres per hour that then is going to determine your bottom drains. Personally I think if you’re going to run anything less than 15 or 18,000 litres per hour you’re going to start to perhaps suffer with issues of settlement in the bottom drain and that is the worst thing you can do. When you build a pond you’ve got to look at the dynamics and basically keep all of your pipework clear and clean all the time.  So, whenever you build a pond don’t look at the pond design and say OK this pond is let’s say 12m long and 4m wide and decide from that you need 3 bottom drains, what you’ve got to look at is the dynamics of it. So, if you’ve got a 30,000 litre intended turnover rate basically, if the pipework runs are not too long and kept nice and simple, you should be able to rig a pond up so you’ve got 2 bottom drains in there with 25,000litres per hour of flow with let’s say 4-5” of head loss on the pipework but the one thing you can be sure of, with the head loss on there the bottom drains will stay clear all the time.  So that’s really the most important thing I think with any pond when you come to think about building it is keeping those bottom drain runs clear.


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Personally I think it’s incredibly bad if you build a pond whereby you allow settlement to occur in any of the pipework anywhere in the system, it’s got to be clean.

Bottom drain pipework installed on Mike's pond

Bottom drain pipework installed on Mike’s pond

Bottom drain placement on Mike's pond

Bottom drain placement on Mike’s pond

Beyond that you’ve got to look at filtration.  I’m not a big fan of mechanical filtration, or should I say pressurised filtration, because to my mind what you’ve got effectively is something very similar to a big teabag whereby you’re using beads or sand to physically trap the waste and then once you’ve trapped the waste you’re forcing water through it.  Therefore any component of that waste that is biologically decomposing is being dissolved into the water and adding to the TDS levels and also discolouring the water. That’s just something that I’m really not a big fan of.

I’m also not a fan of excessive aeration for the same reason we spoke about earlier. I think you need to maintain an O2 saturation of say 80%+ so then you know that if you have issues with weather or power failures everything is OK but I don’t think it’s good to go excessively beyond those levels because at the end of the day you could put 10 times the amount of aeration in there and only get 2% more O2 saturation anyway which personally I think is a wasted effort.

NDI – The system you have running here, you had a blank canvas to build that pond and chose to run ProfiDrum and Bakki Shower. Given you could have chosen any system to run, what was your rationale to choosing that system?

Mike – For that particular system what I wanted to try and recreate was the optimum conditions for trying to raise fish jumbo, the reason being that really more than half the fish that are in that pond already belong to people and a lot of those owners are actually overseas and they are people with big dreams and, because they’ve got big dreams, I’ve got to make sure that those dreams and hopes become realised as often as possible.  So, I wanted to produce a Koi pond that was basically not only perfect in terms of dynamics and filtration but also a good ecosystem for the fish. So, what I opted for there was a pond of 38 tons, which is 8500 gallons, using 3 bottom drains running a total turnover rate of about 83tons per hour, so effectively that’s about 210% per hour turnover rate with about 27,000 litres on average per hour per bottom drain.
When I first went into the ProfiDrums I went to the Holland Show in search of what I thought was the best drum filter I could get for my own use, at the time I wasn’t intending to sell them, and after looking at all the various manufacturers that I could find someone else actually recommended to me that I go and chat to the guys at ProfiDrum and consequently that ended up being the route with it. The idea I like with it is that the waste from the bottom drain goes into the drum filter and effectively gets removed from the system before it gets chance to decompose. Every 10-20 minutes the screen then cleans itself and that waste goes straight off down the drain so you’re then putting water over the showers that is really already very clean in so far as the waste hasn’t started adding to the TDS levels. If you’ve got a pond that’s already very biologically heavily loaded whereby you’re actually physically having to use bacteria to break down the waste it will use a lot more KH, add a lot more to TDS levels and also GH levels so the balance between all the water parameters becomes a lot more difficult to manage.  What I figured with the drum filters, the waste is getting taken out of the system before it decomposes and then there’s a lot less waste to be dealt with by the actual Bakki Showers so therefore the showers aren’t using, or aren’t creating, so much acid by-products so they’re not consuming so much KH and also are not adding so much to the GH or TDS levels.

I went for showers on that particular pond because I wanted to use a system that I’ve been using now for 10 or 11 years because to my mind there are so many advantages with it because of O2 saturation, gas desaturation if you like, or gases being released, and also because none of this is happening with any pressure, it’s all kind of finding its own equilibrium because of the water being able to tumble over the media so freely, so there’s no pressurisation of anything there.  Of course, I think with the showers, if they are degassing, then you need to get rid of the air around them so I think the showers need to be able to breathe properly and be ventilated properly so you don’t find yourself in a situation whereby gases are being broken down and released by the media but effectively getting dissolved back into the water again because the showers can’t breathe properly, so I think this is also important.


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NDI – So in your Bakki Showers you are using genuine Bacteria House media? 

Mike – Personally I wouldn’t use anything else because what I’ve found, and I’ve actually got here 3 copies of Bacteria House, and none of them are the same.  If you took a picture of it and put it on a website people might think ‘oh yeah it’s Bacteria House’ but if you come to use it it’s very different in so far as none of the materials are as hard as Bacteria House.  One of those 3 copies in particular, if you put it into a system and it’s only in there for let’s say a week it’s clearly not been fired properly or it’s not a proper ceramic because that media you can then take out and you can literally break it in one hand which you can’t do with Bacteria House.  Bacteria House is a ceramic, it’s not something that’s made up of minerals that will get dissolved by low KH levels and things like that, it won’t get dissolved by acids in the pond. Bacteria House, basically after you’ve run it for 10 years you can take it out of the system and use it in another system if you want, it’s not something that wears and becomes disposable.   The other thing I’ve also found with it is that Bacteria House is, compared to the copies, a lot more porous, the pores are bigger but also one easy way to see that is to actually literally put it up to your mouth, like a mouth organ, and try and blow through it. None of the copies have got that same kind of porosity, there’s no way you can blow through it in the same manner.  The problem I think is that if the pores are too small like on the copy medias, or alternative medias, that people use, what happens is after a few months the water doesn’t physically pass through the media anymore because basically it’s become kind of jellified and bunged up in the middle.  You then run the risk of creating a bacterial disaster if you like by running that media, whereas with the proper Bacteria House the water does manage to soak and permeate all the way through the media, it won’t actually stay in there and block up and I think that anyone that’s ever run the systems can attest to the fact that if they take any piece of media out at any stage during the system’s life and broken that media open it smells fresh, it looks fresh there is no blocking up going on in there and that’s something you just won’t find with any of the copies that are out there.

ProfiDrum and 2 sets of Bakki Showers are installed in a seperate room behind the pond keeping them out of sight

ProfiDrum and 2 sets of Bakki Showers are installed in a seperate room behind the pond keeping them out of sight

ProfiDrum and 2 sets of Bakki Showers are installed in a seperate room behind the pond keeping them out of sight

ProfiDrum and 2 sets of Bakki Showers are installed in a seperate room behind the pond keeping them out of sight

NDI – The new pond system we’ve discussed has been running here for around 12 months now?

Mike – In actual fact in September 2013 it will be 2 years.

NDI – Is the system still running as it was designed originally or have you changed anything?

Mike – The only changes I’ve done to it, of course I’ve been playing around and watching the parameters really closely,   but basically it’s running as it was in the beginning, the turnover rate is slightly higher than what I was originally intending, I was intending for it to be 38 tons with a turnover rate of approximately 70 tons or 72 tons per hour.  What I found was the bottom drains were working more efficiently than I imagined they would so I found myself being able to up that turnover rate to sort of 82-83,000 litres per hour and that’s using about 600w in total for the 2 pumps.  As far as changes go the only actual change I’ve done is to put in more extractor fans where the Bakki Showers are in order to help them keep breathing properly, basically because of what I said earlier regarding gas levels building up in the filter house and getting re-dissolved into the water so I put plenty of fans in there to ensure there’s plenty of aeration to help the showers degass properly.  The other thing I have trialled is using an air curtain on there to see how that affects the condition of the fish but, after running it for a couple of months now I’ve actually reverted back, as I thought I would, to not using any aeration at all, for me it just seems to work better that way.


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2 Flowfriend pumps deliver a turnover of 82,000-83,000 litres per hour for just 600w power usage

2 Flowfriend pumps deliver a turnover of 82,000-83,000 litres per hour for just 600w power usage

NDI – For any hobbyist out there looking to build a pond is this something you would offer as an ideal system? 

Mike – Personally I think yes, the system is a massive overkill. By that I mean effectively we’ve got a pond that’s 2 tons smaller running outside with half the number of Bakki Showers and that systems not half as good, the difference between the 2 ponds is kind of incremental really, the outside pond which we’ve got which has half the number of Bakki Showers, and a lesser turnover, sure the water’s not as good, but the new one is not twice as good.  Parameter wise it quantifies as being perhaps 10% better on paper as it were.  But I have no doubt that the higher turnover rate makes it a better performing system and a better eco-system for the fish irrespective of what the parameters are.

As far as parameters go I look at a lot of parameters, I don’t just look at ammonia, nitrite, nitrate, pH and hardness, I also look at components of the hardness because one thing that’s important to me is to understand what’s going on within the whole system. At the end of the day if you’re trying to chase low TDS levels and keep those differential levels between raw water and pond water as small as possible I think you need to know what’s contributing to the TDS levels in the pond.  There’s about 14 parameters I test on a regular basis just to see and keep a track on where those parameters are going and one thing that I’ve found is that the main component within the food that adds to the TDS level is actually calcium. Basically the food is pretty rich in calcium and it seems that the food, even when you are running a pond with particularly soft water and low TDS, there’s an awful lot of calcium in the food which the fish just can’t utilise so they excrete it as waste.  Specifically I think that’s the one key component that an over stocked pond will suffer with, a complete rise in calcium levels, especially if the pond is overstocked, overfed and under maintained.
In the western world everyone puts UV lights after the pumps. What people tend to do, when designing a filter system, they go into a settlement chamber, they go through a biological system and then they go through their pumps and through heat exchangers and UVs and that kind of thing and I think that’s a really bad thing to do because, assuming that your pond filter is any good and it’s actually making a good ecosystem, you need that water to go back to the pond alive. I think anyone that’s been to Japan will have noticed that the breeders have got UV lights over settlement chambers and they are doing that for a reason, that reason being is that waste that settles in settlement chambers basically starts to create and release bacteria into the water from the moment that waste stops there in the settlement and the last thing you want is for that bacteria to then go straight through the rest of the system and reproduce in the whole pond.  The UV needs to be over the settlement so all of that festering waste in the settlement is getting hit by the UV all the time and then, after that you then go through your biological bays and back to the pond because then, with any luck your waste is creating bad bacteria whilst it’s in settlement, the UV is trying to deal with that to keep it relatively healthy, the biological bays can then concentrate on making water that’s biologically really nice and very much alive with bacteria and then that bacteria can also go back to the pond and keep the pond alive as it were and I think that’s much much better. I think one of the worst things people can do is put a UV system after the filtration, I think it’s a big mistake.

NDI – I think the general reason for people doing that is a belief that it’s the cleanest water and therefore it won’t make the quartz sleeve get dirty and if the quartz sleeve gets dirty the UV will stop working.

Mike – Yes, it is the cleanest water, but it will also make the most sterile water and I think that sterile water for raising Koi is just no good, the water’s got to be alive, it’s got to be an ecosystem. To put the UV over a settlement chamber you can do it in such a way that you can buy a conventional UV and make a lampshade of sorts for it and suspend it over your settlement bay. Of course you need to make sure it’s safe and you’re not actually physically looking at it all day long but it’s very easy to make it so the UV is shining down into the settlement area and consequently keeping it healthy and allowing your filters to produce good water and good bacteria and make the pond abundant in that.

believer that UV lights should be installed in settlement chambers

The Profidrum installed on Mike’s pond, note the submerged UV light, Mike is a firm
believer that UV lights should be installed in settlement chambers

NDI – Talking of sterile water, around the world people are using things like ozone on Koi ponds, what are your thoughts on those systems?


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Mike – You’ve just struck on something else that I’m not particularly fond of, personally I think people worry too much about ozone levels. The way I see it, ozone to me is something which is quite a potentially dangerous thing to play around with, but also the way I feel about this is that if you’ve got fish that have been properly quarantined and are basically free from bacterial issues they should really stay free of bacterial issues in a pond that’s of a decent design and consequently to my mind you don’t really need to put ozone on there.  The other theory of my own really is that if you are in a situation where you are using ozone to actually oxidise organic levels in the pond you’re not just oxidising organics, that ozone level that’s being put into the pond is oxidising everything indiscriminately, and to my mind this includes the fishes colour, and I think you’ve got to consider the fishes colour as being a living organism in its own right, these pigment cells are literally a living creature that live on the fish and if you consider it that way you look at it slightly differently.  The way I see it is that it’s kind of similar in a way, I think ozone in a way kind of attacks the colour and makes the colour kind of harden up but also makes it become thin so I think that colour doesn’t really last so long on a fish that’s been kept in an environment with high ORP levels and the way I see it is that is you look at let’s say a mudpond, and one thing I’ve done is a lot of testing of ORP levels in mudponds in Japan.  None of the ponds we run here run above 200mV of ORP and the fish generally speaking keep pretty good colour condition long term no problem at all.  I wouldn’t encourage a low ORP but I certainly wouldn’t want to make it high either, what I mean by that is a mud pond typically I’ve found is generally on average 100mV of ORP level and what you’ve got to think about, and this is always something I try and explain to people, is that a new mudpond is an environment for keeping Koi and it really is quite a volatile one and any breeder will say that if they build a new mud pond they’ll never put good fish in their in the first year because at the end of the day any breeder that knows what he’s doing will realise that fish never actually do very well in the first year, or the subsequent 2nd year, and it’s not really until the 3rd year onwards that mudponds start to actually work properly and the reason for that being is that what you’ve got effectively is very very heavily decomposed fish waste that’s in the bottom of the mudpond that kind of makes that sediment or silt but it’s not the same as fish waste that’s built up in a vortex. Fish waste that gets built up in a vortex and stays there too long rots and bacteria can’t get to it but in the mudpond it very different because the fish waste in relation to the surface are on the pond bottom is so small and when that fish waste hits the bottom of the pond the bacteria then work on it and break it down so thoroughly that it almost becomes very much like sinking mud sort of like you’d find in the sea as it were, it’s very similar to that.  What I’ve found is that that mud that’s in the bottom of the pond is very much the same as what facial clays are made of, like anti oxidising clays and I think that what you’ve got there effectively is anti-oxidising facial clays. Basically these are clays that have a negative ORP and it is literally a case of anti-oxidising, I think that the mud pond, any pond that’s mature, the fish do well in there because you’ve effectively got an anti-oxidising environment for the fish, or basically a pond that’s very clean and healthy but doesn’t run a particularly high ORP level because of that negative ORP in the clay at the bottom and I think this is part of the magic of why mudponds work so well. So, for that measure if you like, personally I don’t get hung up on ORP levels on my own pond, I’m interested to know what they are but I’m certainly not interested in trying to raise those ORP levels.  I try to get clean water by justifying it being low in TDS, not high in ORP.  It’s easy to say, well OK the ORP is low we’ll lift the ORP up by using potassium permanganate but at the end of the day you can oxidise all your organics in the pond using potassium but you can still have a high TDS level afterwards so I don’t think there is any point in dressing up your ORP levels in order to deem your water as being clean, you’re much better off using conductivity or TDS levels to determine it’s clean.

NDI – Just to give people some idea of the numbers that are being achieved in the main pond here, what sort of growth rates have you achieved so far?

Mike – There are fish that have been in that pond, they’ve not been in there so long as yet because the pond is quite new, one is 5 years old and about 83cm, but there are quite a few sansai that came in as tosai that are 70cm+ that are in there now. So far I’m quite happy with it but my long term aim with that particular pond is to use it as a tool whereby in a few years time people will come here and they’ll see fish of 85-90cm and hopefully beyond and look at those fish and be able to say ‘wow’ and consequently hopefully they’ll turn around and ask when those fish came into the country and how did they get so big, and I can then turn round and explain it’s not such a big deal but if you concentrate and work on making good water you too can achieve the same thing, that’s the reason for trying to inspire people with a pond that hopefully is performing as well in the future as it has so far.

Mike’s pond provides an incredibly tranquil environment. With no in pond aeration, and sub surface Bakki Shower return weirs there is almost no surface disturbance whatsoever.  Also, because the showers and ProfiDrum are housed behind a concrete block wall, effectively in a room of their own, there is almost no running noise whatsoever.  The Koi also seem to appreciate this, they glide around the pond in a very relaxed manner, when feeding they do so very calmly just rising to casually take pellets from the pond’s surface.

Mike’s pond provides an incredibly tranquil environment. With no in pond aeration, and sub surface Bakki Shower return weirs there is almost no surface disturbance whatsoever.  Also, because the showers and ProfiDrum are housed behind a concrete block wall, effectively in a room of their own, there is almost no running noise whatsoever.  The Koi also seem to appreciate this, they glide around the pond in a very relaxed manner, when feeding they do so very calmly just rising to casually take pellets from the pond’s surface.

NDI – One thing many hobbyists talk about, certainly when I talk to people in Indonesia and the Philippines, are issues with maintaining the colour on Koi.  In some cases I’m sure this is simply down to the fish being wrong to start with, other times people suggest it’s a temperature problem, the fact their pond is naturally too hot, the fish grow so quickly so easily and lose colour, and another thing that perhaps contributes to loss of pigmentation is lack of natural light.  How do you consider those aspects in terms of maintaining colour?

Mike – I think it’s really important to keep the temperature and levels of light in keeping with each other, and I think this is also one reason for giving fish a proper winter.  If you think about it, as far as the UK is concerned, during our winter months we don’t really get as much daylight, the day time is usually pretty cloudy, and if you try to use elevated temperatures and keep your fish growing at the end of the day they are not going to get enough light to keep that colour thriving so you are going to end up with fish whereby the colour is going to look really weak and washed out.  Really you’ve also got to apply the same theory in the summer, if you’re raising fish in the summer you’ve got to think about whether the fish are getting enough light. You don’t want them getting too much sunlight because that will kind of age the colour too much and vice-versa if the fish aren’t getting enough light you need to think about trying to supplement the light a little bit, maybe with things like metal halide lighting, something like that, it won’t save anything from losing colour but it will kind of help a little bit if you are in a bit of a compromised situation.  In Indonesia and other countries like that, like you say, they do suffer a lot with the colour not keeping on the fish, and I think a large part of that is to do with the temperatures being too hot and the fish getting too much sun, the colour’s aging too quickly and then you get an awful lot of teri weakness with the fish because the colours not got a chance to rejuvenate and catch up, which is one advantage you will get with the winter months.  I think with fish that are wintered it’s so much easier to keep them looking youthful once they get big. But, obviously you have to think how you are raising the fish during the summer months to make sure they do get big if you are then going to winter them properly.  So lighting is important and in this regard I think it’s better as well to make sure the fish are getting a lot of light. It’s better to get morning light than afternoon light on them because, although the afternoon light is good for getting the temperature up, it’s also a little bit more intense and runs more of a risk of doing colour damage to the fish. At the end of the day if you’ve got a pond that’s getting full sun all day long the fish really have got nowhere to go, they’ve got nowhere to hide from it. If you’re in a situation where your pond is getting full sun all day long what you need to try and think about is shading it in such a way that, let’s say at 1 or 2pm, they start to get some shade.  If half the pond is shaded, because the fish aren’t entirely stupid, provided you don’t put your auto feeder out in the sun so it drags the fish out into the sunny area, the fish will predominantly try and stay in the shaded area if it’s too hot and sunny for them. It’s better to give the fish the option of knowing what’s best for it.

NDI – One thing connected to the growing of Koi which I’m asked about a lot in various parts of the world is the pushing Koi too hard in terms of growth and development. We’ve seen breeders in Japan who’ve gone to the point that it was a big deal that this was a 70cm nisai etc.,  but now everyone seems to have pulled back because it was making fish too weak, because it was overloading organs and the fish generally weren’t strong enough and you get to 3 or 4 years old and the fish just go belly up and die.  For people in a tropical climate where they can feed all year do you think there is a danger that hobbyists could do just that and grow fish too quickly?


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Mike – Yes, I do subscribe to the theory that much as people in these climates can grow fish easily and have a lot of fun with the fish I think also the success rate doesn’t really work hand in hand with that.  They can grow fish really quickly but also get a much higher failure rate, they can get fish like you say but they look old and haggard if you like because they’ve not got any winter months to rejuvenate and I think, in some regards, in days gone by breeders were trying to push for tosai that were 40cm+ or even 50cm+ and a lot of breeders have now realised in the last few years that they actually ruin an awful lot of fish trying to get them that big and consequently they’ve also kind of come to the conclusion that in actual fact pushing those fish an extra 10cm as tosai doesn’t necessarily mean when the fish get jumbo they are going to get any bigger or grow any quicker. And a lot of these breeders have realised that the success rate of fish, or jumbo tosai, worth keeping is much much higher if they are raised in a slow manner.  I think as you’ve already suggested Mark, a lot of breeders I think do have a lot of issues whereby if they raise fish really big as tosai and then end up with 70cm nisai the fatality rate if you like of those fish not getting as old or as big as they should I think is particularly high. To me, hitting 80cm as 5 years old and then carrying on beyond that is plenty quick enough and not too quick, providing you’re just allowing them to grow and not forcing them and I think there’s a big difference between those two.

Mike searching for jumbo tosai Kohaku at Takigawa Koi Farm, Hiroshima.

Mike searching for jumbo tosai Kohaku at Takigawa Koi Farm, Hiroshima.

NDI – Just a last point really and to bring what I think’s been a very interesting conversation to an end, what most people are under the wrong impression about is that there are 85cm Koi swimming all over Japan, 85cm anywhere in the world is a big fish and therefore it’s important for hobbyists to be realistic with their objectives of what they can achieve.

Mike – Yes you’re right, and you do need the right bloodlines, the right genetics and a breeder with the right kind of business model and then you’ve got to hunt down the fish that are good examples for that breeder.  It’s no good choosing tosai from a breeder of say 35cm and the dealer is saying ‘these fish are jumbo tosai’ when in reality all of the breeders’ best ones are all sort of 40 or 45cm, chances are those ones that are 35cm basically aren’t going to make the grade size wise and that’s why the breeder’s getting rid of them and sold them off to the dealer at a better price. So I think you need to know whatever fish you buy, whether it’s tosai or nisai, they’ve got to be on par for what they should be at that age from that breeder. So I guess in that regard a lot of it comes down to trust of the breeder or dealer concerned, or you own experience of how you should grow fish from that breeder.


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