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Water quality at koi shows


The way water is tested at koi shows is set to change

It is arguable that the most important aspect of a koi show is not the quality of the koi; it is the quality of the water in the display vats. Top quality koi in poor quality water could not be expected to look their best.  Also, anyone looking into the vats would see fish that were clearly unhappy with their present environment.  What would this say to the general public? It would say that the welfare of the fish was being neglected. Owners of koi in poor quality water would be unhappy with the show organisers because they wouldn’t want to see their fish being badly treated, and anyone hostile to koi shows would have the ammunition they need to campaign against them on the grounds that animal welfare was being ignored.

Animal welfare in relation to koi keeping and koi shows is very important. We must be able to demonstrate that we pay careful attention to the fish’s environment, whether it is the long term environment such as in the home pond or the short term environment in the show vat.  So how should water quality be managed at koi shows?  Clearly there needs to be a standardised regime.

Show water testing

Animal welfare in relation to koi keeping and koi shows is very important.

Managing water
Water parameters vary greatly throughout the UK, so a regime to manage water at koi shows must not be specific to just one location, it should be an achievable regime wherever the show takes place. Every koi club throughout the UK should be able to follow a standard set of instructions which are simple to understand and which describe a water management regime and show procedure that adequately addresses all aspects of koi welfare.  Then, with a standardised set of rules to follow, no club or organisation would have to prove, on an individual basis, that their particular show complies with animal welfare legislation. It will be sufficient for show committees to say: “We followed the rules, so every aspect of the law relating to animal welfare has been satisfactorily addressed”. Recently, DEFRA asked for a set of rules for koi shows because of the requirements of the EU and the imminent Transportation of Animals debate.  Scientifically based rules would also demonstrate to the RSPCA, and any other organisation that is interested in animal welfare, that our pets are not being mistreated.

Show water Cl2 test

Prior to koi arriving at the show, water is tested
to ensure it has been properly dechlorinated

A commonly adopted water regime requires that water is only tested every four hours and only for ammonia. In practise, this means that water is tested only two or three times per day which does not really adequately comply with the requirements of animal welfare legislation.  The new water protocol is designed around a three hourly test regime.  The primary pollutant in show vats is ammonia, and the shorter period between tests has a huge advantage where this is concerned. At first, it may appear that water changers would have an increased workload if the period between tests is reduced from four to three hours, but this is not the case. If ammonia is measured every three hours, the earlier intervention means that levels will be much lower and smaller water changes are required.  If levels are only measured every four hours, each individual result will be 33% higher so it will take larger water changes to reduce ammonia to the same degree.  Simple arithmetic shows that, over the course of a day, the total amount of water that needs to be changed will be the same, but with a three hourly test regime there are huge advantages for koi in the show vats.

Taking a simple example to show how fish in vats are affected, consider a vat where the ammonia level increases, from zero, by 0.1 mg/L per hour.  After three hours, the level would be 0.3 mg/L but, if the vat were left for four hours, the level would rise to 0.4 mg/L.  Not only is it far better to intervene at 0.3 mg/L rather than wait until the level had risen to 0.4 mg/L, but it only takes a 33% water change to reduce 0.3 mg/L to, say, 0.2 mg/L whereas it takes a 50% water change to reduce 0.4 mg/L to 0.2 mg/L. Three hourly testing means lower ammonia levels and smaller water changes; both are less stressful to the fish.

Show water entrance

Biosecurity is important

Show water George

Hand disinfection station

Dissolved oxygen
Another water parameter in show vats is dissolved oxygen. The importance of this parameter is being raised to a higher level in the new show rules.  The generally quoted figure for the minimum acceptable level of dissolved oxygen for koi is 6.0 mg/L and this is currently the recommended minimum level at many koi shows. In the new submission to DEFRA, this will be raised to a recommended minimum level in show vats of 7.0 mg/L which better fulfills the requirements of animal welfare legislation. By increasing the minimum level to 7.0 mg/L, a reservoir of oxygen is built up in the water which allows for occasional short interruptions to the air supply. Some are accidental such as a short power cut. Some are deliberate, such as the temporary removal of air-stones to allow better visibility during judging or photography.

If a vat was already at the minimum acceptable level, (6.0 mg/L), when the air supply was interrupted, it would soon fall below this level.  Not dangerously so, but it would undeniably be below the recommended minimum and this would breach animal welfare standards.  It therefore makes sense to raise the minimum level in show vats and to test more frequently.

Another reason to frequently test for dissolved oxygen and to ensure that there are higher levels of aeration in show vats is the effect that it has on ammonia levels. High aeration is beneficial in two ways. The greater the degree of aeration, the less ammonia the water can hold. Water can only hold a certain amount of dissolved gasses.  By increasing the amount of oxygen in the water, there is less “space” in it for any other gas, such as ammonia.  In other words, by “pushing” oxygen into water, it “pushes” out some of the ammonia that is already in there. Another effect of increasing the oxygen content of water is that it counteracts the effect that ammonia has on the capacity of a fish’s blood to carry oxygen.

Koi welfare at koi shows
is the main priority

Show water floating

The travel bags are floated
to equalise temperatures


Show water release

The koi are released taking care
not to allow bag water into the vat


Show water guide

Koi are guided towards the bowl
without touching them with the net


Show water measure

 After inspecting and checking classification, koi are measured


Show water photograph

Koi are photographed to assist identification during judging


Testing show vat water
When testing water parameters, samples are taken from each vat by a bio-secure method. My personal favourite method is to take a 40 ml sample in a special sample cup with a raised handle which avoids the risk of accidental hand contact with the water.  Taking a 40 ml sample with a cup rather than a 10 ml sample with a syringe means that far more can be done with this larger sample than just an ammonia test.  If samples are taken and brought to a central testing station, there is no risk of compromising bio-security by dipping measuring equipment into the vat water.  No electronic measuring equipment needs to be disinfected between tests with the risk of aggressive disinfectants damaging the probes, only the sample cups touch water in the vats and, like nets and other equipment, these can quickly be disinfected and rinsed before re-use.

Dissolved oxygen can be rapidly measured with an electronic oxygen meter but this must be done immediately after the sample has been taken because the oxygen level in the sample will soon begin to fall after it is removed from the highly aerated vat.  We do not need to know the precise level in the vat.  The new minimum standard for oxygen in show vats is 7.0 mg/L.  Whilst dissolved oxygen is a very important parameter, as long as every sample is tested within about a minute of being taken from the vat and is confirmed to be well above 7.0 mg/L, the precise value in the vat is less important than the knowledge that it will always be slightly higher in the vat than when it is tested at the testing station. Interestingly, by measuring dissolved oxygen accurately with an electronic meter, the effects of temperature variations throughout the day on dissolved oxygen levels can be seen.  Cooler water can hold slightly more oxygen than warmer water. At our show in August, the early morning tests, when the water is at its coldest, averaged around 9.5 mg/L. When water temperatures increased as the air temperature rose, a small decrease was recorded so that, by mid afternoon, when water temperatures were higher, oxygen levels averaged around 8.5 mg/L. They began to rise again as water temperatures began falling in the evening.

Water temperature
Temperature is another parameter that should be monitored regularly. Using a non-contact infra-red thermometer, it is simple to measure water temperatures in each group of vats immediately prior to taking water samples. For koi shows to have a future in the UK, we must do everything possible to demonstrate to anyone hostile to koi shows that our koi are not being mistreated. In reality, with the exception of heaters in vats, there is little that can be done to minimise diurnal (day to night) variations in water temperature. Vats can be shaded from the sun during the day, but air temperature, especially when windy, has a greater effect on the water temperature in the vats.  The new show rules recognise this and define sensible temperature standards and a test regime that are both easily achievable but which should be adhered to. Since water temperatures can be measured by means of an infra-red thermometer and then recorded within a few seconds, it makes sense to do this for each vat every three hours as part of the scheduled water tests.  This is a requirement of the new show rules and it has been deliberately included because, although it takes very little effort to accomplish, it demonstrates to koi show supporters and to those who look for reasons to ban koi shows that everything possible is being done to monitor the welfare of the fish in the vats. This is well worth the few minutes extra work it involves every three hours because it is a clear case of maximum brownie points for minimum effort.

Measuring pH
The new show rules recommend regularly measuring pH. This need not involve any extra time.  I prefer water samples to arrive at the testing station in batches of five and immediately measure dissolved oxygen as described above. The second task is to fill the cuvettes and add ammonia reagents to them so they may develop ready for measuring.  Developing time is 3½ minutes using a Hanna photometer.  This is sufficient time to measure the pH of the remaining water in the sample cups using a pH meter. Disinfecting it between tests is unnecessary because it never comes into contact with the water in any vat, only with the water in the sample cups, so it can quickly be transferred from one sample cup to the next whilst waiting for the reagents to develop.

Why measure temperature and pH at every scheduled round of ammonia tests?  The effect of ammonia is very dependent on pH and temperature.  Recommended limits for ammonia in vats take this into account.  We could just take the pH and temperature of one vat at an arbitrary time and assume that this will apply to all vats throughout the whole day, but since these parameters will vary and are easy to measure and are so important when deciding what ammonia values are acceptable and what are unacceptable, I would turn the question around and ask “why not”? The more we are seen to care about animal welfare, the more likely it is that koi shows can continue.

Syd Mitchell