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Food for thought     (Food for thought)


These are my thoughts on a range of topics - what are yours?

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Can fish feel fear?
Living creatures that are potential prey for predators can adopt one of two main strategies. One strategy is to simply out-breed the predation rate as many insects do. For example, aphids feeding on a plant will continue feeding even though a ladybird is amongst them eating as many as it can. No matter how many aphids the ladybird eats, the rate at which they reproduce is so high that predators can't eat them all and the colony will survive. A second strategy to a threatening situation is to exhibit a "fear response" that causes potential prey to adopt a behaviour that gives each individual a good chance of survival. This might involve standing their ground and fighting off an attack or getting out of the threatening situation as quickly as possible. In general, fish are not equipped to fight so the usual strategy is to swim away and hide.

Since it is obvious and well known that sudden or threatening movements near a pond will cause the fish to immediately react in a defensive way, it needs no further proof that there is a fear reaction of some kind taking place, but is this similar to the human concept of fear? I believe it is and this is my reasoning.

The fear response in fish is measurable by analysing blood samples since this response causes a chain of reactions including the release of several hormones, such as cortisol and epinephrine, into the bloodstream. These shut down all body functions that are non-essential in the short term such as digestion, the immune system and growth etc. They also increase the heart rate, respiration and prepare the muscles for a sudden explosive release of ATP (adenosine triphosphate). ATP is a complicated chemical but, amongst its other functions, it can be regarded as giving muscles their power to perform. All animals, including humans, use ATP. If you need to run away from a tiger, you need all your muscles to perform for a short time at far higher power than normal or you will be eaten. An explosive release of ATP is what allows them to do this.

What is happening when the fear response hormones are being released into a fish's bloodstream is that all body resources are being made available to react to the situation, and in carp, this means to get away from a threat as quickly as possible. As soon as the situation becomes safe again, these hormones are no longer being released, the heart rate and respiration return to normal and the other suspended functions, such as digestion and immune system etc can resume. But blood sample analysis shows that, if a fish cannot swim away from danger, or an environment it doesn't like, these hormones persist.

When humans are exposed to a dangerous situation, whether it is accidental like suddenly being chased by a tiger, or whether the situation is deliberate as in the case of bungee jumping or white water rafting, we get the "adrenaline rush" feeling. This is due to stress hormones being released into our bloodstream and our body's reaction to them. Our fear response can be unpleasantly frightening or deliberately stimulating according to taste, but even if an individual enjoyed a short term deliberate stimulus, would living in danger with no chance of escape still be enjoyable? I think not. Living in continuous fear would be unpleasant.

And this is where I believe we can draw an analogy with fish. Whether it can be argued that the "fight or flight" reaction to a short term threat might not cause them any great distress, the continuous release of epinephrine and cortisol etc into the bloodstream as a result of a permanently stressful situation will cause a continuously elevated heart rate and respiration. These hormones also cause reduced digestion, immune system etc. I would argue that if the fish cannot resolve this unnatural situation by swimming away to safety, it would be similar to the human concept of living in fear.

Can fish feel pain?
It is often argued that fish cannot feel pain. I take the opposite view based on research into fish behaviour by L. U. Sneddon in 2003. In this research, rainbow trout were given injections of bee venom and acetic acid in their lips. Their respiration rate increased and they didn’t feed for three hours. They were also observed to be rubbing their lips against the sides of the tank and rocking from side to side on their pectoral fins during this time. To test whether this was a reaction to the venom or to the injection itself, a control group were given a saline injection. This control group didn’t show a great increase in respiration and resumed feeding in a little over an hour. This showed that although a harmless saline injection caused a slight change in behaviour for a short time, an injection of bee venom and acetic acid caused a greater behavioural change for much longer. Did this prove that the fish experienced pain from the venom injection but not from the saline injection? The research went one stage further. The experiment was repeated but this time the fish that were injected with venom and acetic acid were also given a pain killer, (a morphine injection if I remember correctly), and this produced a noticeable reduction in the rubbing behaviour with no increase in respiration.

So to sum up the way I understand the research: A harmless saline injection in the lips produced a short term slight behavioural change. An injection of bee venom and acetic acid produced a longer term reaction of increased respiration, rubbing the lips, rocking and not feeding. An injection of venom and acetic acid followed by a pain killer produced less reaction and no increase in respiration. In my opinion, that proves that there is a definite pain response in fish and it is similar in nature to how a human would react if they were the subject of this type of experiment and I think it proves that fish can feel pain in much the same way as a human.

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Keeping sturgeon with koi
No animal or fish should ever be bought on impulse and this is especially true of sturgeon.  They can successfully be kept in a pond along with koi but they require a different care regime and slightly different water parameters. These differences and the extra care aren’t great, but potential purchasers should be aware of them before considering whether to add sturgeon to their pond.

Where water parameters are concerned, the most important differences are dissolved oxygen and pH.  The minimum dissolved oxygen level for koi is usually quoted as 6.0 mg/L but in reality, although lower levels are not to be encouraged, koi will survive at lower levels than that.  This doesn’t mean that they will thrive but they will survive.  With sturgeon, 6.0 mg/L really has to be considered as the absolute lowest level allowable because they are particularly sensitive to dissolved oxygen levels.  They are likely to die very quickly if the level should fall even though koi in the same pond may not be showing such a marked degree of distress.

The optimum pH range for sturgeon is 6.5 to 8.0 and the pH range for koi is 7.0 to 8.5. Other ideal water parameters for sturgeon and koi are similar which means that if the pH is kept in the range 7.0 to 8.0 and if oxygen levels are as high as is possible then the water parameters of a koi pond will also suit sturgeon.

The nutritional requirements of sturgeon are another difference. Koi can eat a wide range of food but sturgeons require a specialised diet.  They will eat whatever is available but, being carnivorous, they don’t have the correct enzymes or gut bacteria to be able to digest plant protein. Koi food with high protein content will be indigestible if the protein is plant based. Like koi, sturgeon can eat treat foods but the range is limited and the basis of their diet must be high in animal proteins such as fish meal as is found in specially manufactured sturgeon food. They will obtain little or no nutritional benefit from the wrong type of food.  If sturgeon cannot obtain sufficient nutrition from what they eat, they will firstly metabolise any stored body fat, then after that they will subsist by living off of their own muscle tissue.  This causes them to develop a distorted body shape and even become bent which is a sign that death by starvation is imminent.

Their normal feeding habits should also be understood. In their natural environment they have evolved to feed by continuous browsing which has resulted in them only having a small gut. As a result they cannot eat much at any one time and in a pond environment they fare better if they are fed several small meals per day.

If these different requirements can be accommodated, there is no reason why sturgeon should not be added to a koi pond and mix well with its existing inhabitants.  There is, however, one final point to remember if ever a pond treatment is needed.  Treatments containing copper, copper sulphate, formalin or potassium permanganate are poisonous to sturgeon so they should be removed during these treatments and treated separately, possibly with a high strength salt bath because sturgeon are more tolerant to salt than koi.

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Fresh food
When reputable manufacturers produce koi food, they aim to ensure that it fulfills all the dietary needs of koi and they proudly put the list of ingredients on the package or bucket, but is that nutritional information still valid on the day the fish eat it?  As long as the “use by date” isn’t exceeded, there will be no threat to the fish resulting from them having eaten food that has gone off but that doesn’t mean that it won’t have lost some of the nutritional value that it had on the day it was first opened.

Vitamins are organic compounds and they will begin to degenerate when the bag or bucket is opened and they are exposed to the air. The same process begins as soon as proteins and oils in koi food are exposed.  Manufacturers try to overcome this by choosing ingredients that resist degradation but there are limits to what even the most conscientious manufacturer can achieve.  Whilst correct storage will minimise any nutritional losses, I would argue that supplementing a staple koi food with additional fresh food can only be an improvement to the koi diet.

The expressions “essential minerals” and “essential amino acids” are often used in relation to diet or nutrition.  The word “essential”, not only means that the particular nutrient is necessary for a healthy metabolism but it also means that the body cannot manufacture it from other dietary nutrients. Therefore if any particular essential mineral or amino acid isn’t present in sufficient quantities in the diet of a fish or other animal there is no way they can obtain it by metabolic processes from any other nutrient.

To avoid a deficiency in the human diet we are advised to eat a wide range of foods in order to increase the range of vitamins, minerals and other nutrients our bodies have available to use. If that advice makes sense for me, it makes sense for my fish. For this reason I would always recommend that koi are fed primarily on a good quality koi food but supplemented by a wide range of fresh foods.

Prawns are a good source of protein as are earthworms from the garden provided there is no chance that they may have been exposed to any garden fertilizers, herbicides or pesticides. Fresh fruit of any kind is a sure source of additional vitamins.

A highly recommended fresh food for koi is lettuce.  It is rich in vitamins A and C, and contains essential minerals and significant amounts of all ten amino acids that koi need.  There are different views on how to feed it to koi, one way is by tearing off individual leaves, another is to throw a whole lettuce into the pond and allow koi to tear it apart themselves. The only word of caution I would add to this method is that I did hear of one large koi who, after all the leaves had been eaten, thought he would eat the remaining stump. He managed to get it into his mouth but could neither swallow it nor spit it back out. It remained stuck and had to be removed under anaesthetic. If you have a koi large enough to do the same, it might be better to avoid that risk by first removing the stump.

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Which is better; hard water or soft water?
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 or lower and rarely going higher than 46 to 48 mg/L.  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 responsible for skin 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, the pigments 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.  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. On the other hand 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. 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°dH.

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Is clay necessary?
There isn’t a definite answer to whether clay is a necessary additive to koi ponds, it entirely depends on the exact make up of the water chemistry but it does have benefits.

Koi, and other fish, need a wide range of minerals and trace elements in their diet. Food manufacturers try to ensure that their product contains everything a koi needs but fish also take in dissolved minerals direct from the water by absorbing them chiefly through the gills and gut.

Carp will eat whatever they can find.  In the wild, they find a wide range of food which helps ensure that they obtain everything they need to stay healthy.  Some of this food is found by rummaging through the mud at the bottom of their lakes which means that, when worms or insects are eaten, some of this mineral rich mud is also swallowed. Rotting organic material from plants or even dead fish is also broken down by bacteria in a process called mineralisation which releases minerals back into the water to dissolve and be available to be absorbed by other fish.

In contrast to a natural pond, we try to keep koi ponds as clean as possible.  We don‘t allow detritus to build up and then decompose into its component minerals so it becomes our job to supply our koi with everything that they need.

When a pond is filled, it contains minerals from the mains water supply unless they have been removed by a purifier. Water changes and top ups help to replace those minerals as they are used but there is a difference between water in which koi can survive and water in which they can thrive.  This leaves the question; will water changes alone add sufficient minerals and trace elements, and will these be the correct ones anyway?  Pond clay can ensure that pond water doesn’t become mineral deficient.

Minerals introduced by adding clay vary according to where it was mined. Bentonite clay is particularly rich in calcium.  Calcium cannot be synthesised by fish and is vital for strong bones and scale development, it is a catalyst for enzyme action and other metabolic functions but it has other benefits as far as pond water is concerned.

Calcium has what chemists call “a negative electrical charge” which means that as this type of clay settles slowly to the bottom of the pond it will attract positively charged impurities to it. Although calcium molecules don’t actually remove impurities from the pond water, nor can calcium make the impurities vanish, they will be permanently locked together and, as such, they cannot affect the fish. Then, when the clay is filtered out as sediment in the filter bays and flushed away, it takes those pollutants with it.  In this way, toxins such as heavy metals, free radicals, and pesticides are removed from the pond.

There are other benefits to pond clay but there could be a drawback if it is used excessively since all pond clays increase both pH and hardness.  Koi are tolerant of a wide range of pH and hardness provided the actual levels are stable and do not vary abruptly. They are particularly sensitive to variations in pH of more than 0.2 per day, so if clay is used, the recommended dose rate shouldn’t be exceeded.

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Predator protection
The original Magoi from which koi as we know them today were bred, were dark and inconspicuous which made them less noticeable to predators but selective breeding has produced the brightly coloured koi we now keep in our ponds making them a much more visible target.  Arguably the most common predator that a koi keeper has to guard their pond against is a heron.

A common deterrent is the plastic heron. It is said that placing one of these by the pond will be a good deterrent because herons are solitary, territorial birds so a real heron flying over will assume that spot is already taken.  Herons are intelligent and are not so easily fooled. If a real heron sees the same replica bird in the same position every day, it may be deterred for a while but they will soon learn that its “rival” is a fake. One amusing story I heard tells of a real heron that had become so used to a fake heron that it used to land on the decoy’s head in order to use it as a vantage point to look for the best fishing position in the pond.  If decoy herons are used they should be regularly moved in order to keep up the deception.

I once had a heron problem and used the fishing line technique to prevent herons getting into my pond. I placed strands of strong fishing line around it as a barrier. This worked well for a while and we would occasionally see a heron walk around the pond, leaning against the line looking for a way in until it realised it couldn’t reach my koi and eventually flew off in disgust.

For some unknown reason, foxes soon began chewing through the fishing line leaving gaps where the heron could enter. I solved this problem by replacing the line with an electric fence. These give predators a short, sharp “zap” which doesn’t harm them but is sufficiently unpleasant that it makes a good deterrent.  The voltage deters many other predators but isn’t sufficient to affect a heron because their feathers are too thick and act as insulation but it still provides an effective barrier and no fox or other animal will want to chew through it and leave an entry point.

Other predators that are easily deterred by an electric fence include the mink that have now set up breeding populations after having been released by well intentioned, but misguided animal liberation campaigners.  Mink are voracious predators that have devastated indigenous wildlife populations and see a koi pond as just another feeding opportunity.  They are mostly nocturnal so they are unlikely to be seen, although their pattern of attack can give them away.  They pull fish out of the water and begin to eat it either from the head or from the tail to prevent it flapping around while they are eating it. If the fish is too large for them to eat as one meal, the half eaten remains showing signs of being consumed from one end can indicate that the attacker was a mink.

For an electric fence to be a deterrent against mink or similar predators, an additional strand should be placed just above ground or coping level to prevent them slipping underneath the higher strands.

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The overuse of chemicals
Many koi keepers reach for a bottle of their particular favourite medication at the first sign that their koi are behaving in any unusual way but is this course of action the best approach to adopt? I would say not.

OATA estimates that 90% of fish deaths are primarily caused by incorrect water parameters. This doesn’t mean that in every case they will have been poisoned by bad water. Some will have died as a direct result of poor water quality but the majority will have been weakened by it so that they fall victim to something they might otherwise have been able to resist.   If koi look or act as if they are unwell, it’s always advisable to firstly ensure that all water parameters, especially the oxygen level, are acceptable and to quickly correct any parameter that isn’t.  This may well prove to be all that is necessary.

If water parameters are satisfactory and the fish still look unwell, the next action to take is a proper diagnosis before treating even if this means calling for help from a professional or someone with greater experience.

Adding a treatment to the pond in the hope that it will be the right one isn’t advisable.  Formalin and malachite green (FMG) is effective against a range of koi parasites but it isn’t a “cure all” treatment that is effective for all ailments. If this was the case there would be no need for koi dealers to stock anything else. As with other medications it has its uses but it also has side effects.  There are sufficient indications that malachite green is carcinogenic for it to have been banned as a medication for food fish because it breaks down into a compound called leucomalachite green which persists in such tissues as their liver, kidneys and muscles long after they have been treated.  There are no studies that I am aware of into whether tumours in koi can be caused by leucomalachite but it seems sensible not to use the treatment more often than is really necessary.

Another effect of FMG is that it lowers the oxygen level; each 5 mg/L of formalin removes 1 mg/L of dissolved oxygen from the water. A fish gasping at the surface may be exhibiting a symptom that it has been infected by a parasite or it may simply be a sign that the oxygen level is low.  Treating the pond with FMG in such a situation and lowering the oxygen level even further may be the last straw resulting in the rapid deterioration of the fish’s condition or possibly even its death.

Potassium permanganate is another chemical that is frequently used at the first sign of trouble but it’s aggressive and shouldn’t be used without care. Last year, at a koi show, a mobile phone was thrust into my hand so that I could give advice to someone who had treated his pond with potassium permanganate and whose koi immediately began dying.  The story is in the health pages of this site and, in essence, it was about a man who followed some poor advice about dosing with potassium permanganate at the first sign of trouble but without the warning that it’s a very aggressive chemical and shouldn’t be used unnecessarily or without due care. It’s a good example of the dangers of over using a chemical at the first sign of trouble.
(Click to read the full story)

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The uses and misuse of salt
When I first became a koi keeper the general advice at that time was that salt was a good medication and should always be added to koi ponds because it protected them from parasites, especially over winter. Today salt is still recognised as a good medication but, fortunately, the advice that salt should be a continuous additive to koi ponds seems to have declined.

Whether salt baths are effective at killing parasites depends on the parasite never having experienced salt prior to being put into the high strength salt solution. Simple parasites are killed by salt as a result of what is called osmotic shock. When a parasite is suddenly exposed to a high level of salt in a bath, osmosis causes water to be drawn out of them so quickly that they die from dehydration within a few minutes.  The sudden shock of being exposed to salt is lost if it is used continuously at a low level in a pond because any parasites that enter the system will have time to build up a resistance to it. They do this by altering their internal body fluid chemistry for a more saline one which suits the salty environment. Then, when the parasite is placed in a salt bath, it may not be killed because the scale of the sudden increase will be reduced by the fact that it already will have partially adjusted to a saline environment.

It is also now recognised that salt isn’t as harmless to koi as once was thought.  The carp from which koi have been bred have evolved in fresh water which only contains trace amounts of salt.  Since their body fluid has a slightly higher salinity, this means that water continually enters them due to osmosis via the gill and the gut. Carp kidneys are very efficient at expelling this water and use it to also expel dilute urine from which as much mineral content as is possible has been extracted. This is called the osmoregulatory system and it is very finely balanced.

There are some medicinal advantages to putting sick koi into a saline hospital tank while they recover and these advantages outweigh the disadvantages in that situation.  However, where salt isn’t required for its therapeutic value, the long term negative impact on the osmoregulatory system caused by subjecting it to a permanently saline pond and upsetting its fine balance must be considered.

Salt in the pond is also said to help the immune system protect koi against parasite attacks by increasing the mucus coat. This coat is the first line of defence against such attacks so the theory says that any increase in mucus must increase the protection. This is only partially true because although extra mucus will help to a small extent it hides a greater problem.  Firstly the coat only thickens as a result of the salt being an irritant and the extra mucus production is the koi’s attempt to lessen the irritation and secondly excess mucus also occurs in the gills.

As the gill lamella become blocked by excess mucus their efficiency and rate at which they can extract oxygen from water and remove carbon dioxide from the bloodstream is reduced. A reduction in blood oxygen level reduces the immune system that the salt was intended to assist.

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Culling koi
Senbetsu; I’ve never done it or seen it being done in real life, only in videos, but the rate at which breeders can separate potentially good quality koi from those that wouldn’t even make “garden centre” grade fascinates me. Senbetsu translates from Japanese as “selection”. When used in reference to koi breeding it refers to the art of culling koi.  This isn’t for the squeamish because the expression “culling koi” could just as easily be replaced by “killing koi”.  Some will argue that the process of selecting which of the koi fry will live and which will die is unpleasant, but does that make it morally wrong?

Nature has evolved a strict culling process on all species including fish. On a purely numbers basis, if all the fry from two parent koi throughout their breeding lives were to survive, even the largest lake would rapidly be overstocked. All would be at risk of starving to death due to insufficient food supply or succumbing to the poor water quality caused by such a massive population.  And that is from just two parent fish; just imagine if all the fry from all the other adult fish also survived.

Fortunately that doesn’t happen because nature’s own culling rate is astronomical. For a breeding population to remain stable in size, on average taken over several years, out of all the fry that hatch, the total number that survive to adulthood must equal the number of adults that have died during that period.  If any more than that number survive and begin breeding themselves, overstocking, and all the problems that would bring, is a certainty.

Nature’s culling procedure for carp could be said to be loosely based on two criteria. Weak or deformed fry will grow slowly, if at all, and will soon be eaten, possibly even by tobys from their own spawning. Tobys are the fry that grow very much faster than their siblings and soon become large enough to eat those that haven’t grown so quickly.  This is broadly similar to the first culling criterion adopted by koi breeders; the weak and deformed fry are removed.  Tobys must also be separated and, if they are to be kept, they are raised separately to prevent them eating their slower growing relatives.

In removing the weak and least likely to survive, breeders are only emulating what would have happened in nature.  I don’t think that is morally wrong.

A second criterion, when nature is busy reducing natural populations, is culling according to colour and pattern.  Natural selection by predation removes the most conspicuous.  The most brightly coloured are soon spotted by predators and eaten. Breeders do this too but the other way round, selecting the dull and least attractively patterned to be culled and keeping what nature would call the most conspicuous but what koi keepers would call tategoi, which translates from Japanese as “keepkoi”.

Breeders may recoil in horror at the above crude description of the art of senbetsu. It is far more complex than just weeding out the deformed, weak or least brightly coloured but this short article isn’t an attempt to define senbetsu it is merely my opinion on whether it is morally wrong. I don’t think it’s so very different from nature and so therefore it can’t be.

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Butterfly koi
To declare my position from the start, I don’t like butterfly koi. To me they just look wrong and couldn’t be entered in a UK koi show that is run under JSC judging standards or any other show judged under ZNA standards. In America, where butterfly koi have gained greater acceptance, there is a special class for them at shows but under ZNA and JSC rules they would fail the first test - body conformation. Standards relating to body conformation clearly define how a koi should look and that expression doesn’t just define the body but the fins as well. The actual body of a butterfly koi isn’t too far from the ideal shape for true koi, but the size and shape of their fins rule them out completely.

Butterfly koi aren’t even true koi, but a hybrid that was originally called a Dragon Carp, so it would be easy for me to fill the rest of this piece with reasons why no true koi keeper should have one in their pond but, when judging koi, there is an underlying rule; “appreciation, not assassination”. This means that, when judging, the object is to look for the good points in a koi rather than points that could demerit it so I shall try to be positive about butterfly koi.

Butterfly koi may even grow in popularity. Consider how the koi we know today have changed in a very short time.  In Japan, carp were originally only bred for food until farmers, notably in the Yamakoshi village in Niigata around 200 years ago, saw red and yellow colour mutations in some of their stock.  They began the selective breeding to enhance these variations that has resulted in koi as we know them today. When this process first began, the original magoi breeders may have looked with disdain at the farmers who had noticed those small variations in colour in some of their stock and began to try to enhance the mutations. Isn’t this similar to what is happening with the breed now known as butterfly koi?

There are various opinions as to their origin but the general consensus seems to be that they are a hybrid that was produced by crossing ordinary koi with some type of Asian carp, probably the Indonesian long fin carp. It is possible that some lines of butterfly koi have different origins as breeders try different spawnings to enhance different characteristics.

Now that the breeding line is becoming established, even “proper” Japanese koi breeders, such as Toshio Sakai, have joined in and have begun breeding Hirenaga or Hire Naga koi. The breed is so new that even its name isn’t yet fully established.  In the Japanese kanji writing system, hire means fin and naga means long so it’s probable that the combination of the two words, Hirenaga, will become the accepted name.

Given their popularity, and the fact that Japanese breeders are now producing them, it’s likely that butterfly koi will eventually become accepted as an established koi bloodline, just as those mutant carp have now become accepted. Heaven forbid, if there is sufficient public demand we may even see them at UK koi shows. That’s fine, popular demand must have what it wants and butterfly koi may soon become a common sight - just not in my pond!

Back to topic list         More food for thought