Major challenges facing koi keepers as the weather warms up

This is an article I wrote for Koi Carp Magazine that was to be published in their Magazine early in 2007.

Get Your Pond in Order BEFORE Spring Arrives ...

1) Water warms up

For the vast majority of koi ponds in the Northern hemisphere the winter water temperature drops below 8 degrees Centigrade for considerable periods of time and at this temperature koi tend to switch off their physiological systems, and conserve energy by remaining motionless on the bottom of a pond.

In many shallower koi ponds it is possible that surface ice could have developed which means that the temperature of water underneath the ice varies between zero degrees just below the ice surface to 4 degrees at the bottom of the pond.

Remember water freezes downwards because water has a most remarkable property ... its density is highest at 4 degrees. This property allows living creatures to survive freezing temperatures in natural lakes and rivers.

However it's not just the koi in the pond that conserve energy. Most microorganisms and larger creatures do the same which simply means that almost all life in the pond hibernate to some extent.

If a winter is prolonged then fat reserves of the koi that were built up when water was warmer and feeding was good are depleted and this is the start of pond problems that so often occur in koi ponds as the weather warms up.

In this regard Koi are like you and me ... if we eat less, and if we don't care for our bodies by eating the right foods with the essential vitamins, trace elements and proteins then our natural defenses are weakened considerably. We don't die but we become susceptible to attack by bacteria and virus diseases for the simple reason our immune system has been weakened. The bacteria and viruses were always around us but we were quite able to ward them off owing to the resilience of our immune systems.

2) What stress and/or damage can they have suffered during the winter months?

The comatose state that koi enter into in prolonged low water temperatures is normal.

They stop eating and are actually quite stress free while in this state since the microorganisms are not active enough to create stress conditions and pond oxygen levels tend to be at their highest (cold water holds more oxygen than warmer water). However the stress risk increases exponentially as soon as the water temperature and hours of sunlight increase.

Such changes in the environment are like an alarm clock to pond inhabitants large and microscopic. The bacteria and viruses that were present are now hungry ... they look for food and hosts to provide all their other needs.

They multiply quickly ... almost everything in nature speeds up as temperature increases including the break down of all organic materials.

If the Koi in a pond have depleted their fat reserves, if they have low levels of immunity then they are prone to bacterial and viral and fungal attack at this stage without a shadow of doubt.

On the other hand if they had been fed well the previous year and been fed periodically during winter (only as necessary ... ie when the fish is swimming around) with a high quality highly digestible food then they will probably not be stressed at all. Quite the opposite ... they will welcome the new conditions and revel at the expectation of great things to come. Koi are genetically built that way.

3) When should you start feeding them; how much, and what kind of food?

Unless Koi are comatose and lying motionless for long periods they should always be offered food. The trick is to feed them tiny amounts of the right foods. If Koi are fed then it is vital that any food not eaten after a short space of time is removed from the pond. This quite simply means floating food is essential. For many years wheatgerm-based formulations have been the food that almost everybody has promoted but my view is that this is rarely good enough since it lacks the balance the fish requires. The fact that water is colder does not mean Koi do not need vitamins, trace elements and a full range of proteins in the food. The right food should be high quality, well formulated; highly digestible food ... the food you would feed in summer except it should be offered in tiny quantities.

4) What illnesses are they prone to as the water gets warmer? What signs should you be looking out for?

Koi are prone to viral and bacterial attack. In fact attack by all microscopic organisms with the real dangers being posed by bacteria. Ulcers which are so often rampant as water warms up are a common Koi disease and are the result of minor scrapes and exposed body damage being entry point to virulent attack.

Since the Koi's immune system has been weakened by its over-wintering the initial attack it is not able to be resisted sufficiently well using natural methods and the bacteria now get a much greater hold and multiply at an enormous rate made possible by an initial viral infection.

This situation is worsened by the fact that the biofilter is also sluggish since the aerobic filter bacteria are also metabolizing very slowly as well owing to low water temperature. Under these warmer water conditions of increasing viral and bacterial growth, and increasing ammonia and nitrite levels the potential for disease breaking out in any koi pond also increases dramatically. Compare the situation to a cold that becomes pneumonia in humans ... the cold we are all familiar with.

The common cold is a viral incurable affliction that has a short lifespan and is eventually overcome by the body's natural defense mechanisms. The viral attack is thus not dangerous. What is dangerous is that if we are really run down, undernourished, living in cold and damp conditions then the viral attacks makes it possible for the pneumonia-causing bacteria to invade our lungs and then we become really sick and are faced with a potentially life-threatening bacterial disease. Any unusual behaviour and especially body growths, sores, ulcers are signs to be taken seriously.

5) Why is aeromonas a threat, and what can be done to minimize this threat?

Aeromonas are bacteria that cause ulcers and often the death of Koi. They are always present in every pond and they obey laws of nature ... give them food they grow, give them correct water temperatures and they grow more quickly, give them weakened hosts and they will breed prolifically.

Aeromonas also compete for this environment with filter bacteria, and other microorganisms in the pond and only the fittest survive. There is a natural process known as "Competitive Exclusion" which in its simplest form says ... if 2 organisms compete for exactly the same territory only one of them will survive. And that will be the stronger.

If pond conditions favour Aeromonas more than other forms of bacteria then Aeromonas will take over and become a much greater disease risk. The only way Aeromonas can be controlled down to low (even zero) levels is to fight it with fire as it were ... to introduce much more benign but stronger bacteria that competes for exactly the same food and conditions favoured by Aeromonas. In this way the fitter of the two will survive. Bacteria available commercially that provide this destructive Aeromonas power are called KoiZyme or Genesyz.

6) Are there 'vitamins' that you can give your koi to boost their immune systems?

All the vitamins and trace elements and other essential requirements are contained in well balanced high grade koi foods produced by respected manufactures. My view is that there is no need to add anything else to supplement a high quality koi food from a respected manufacturer except the occasional live food or green food. The question of the right food is so important that a few years ago I wrote an extensive article and created a specific calculator that is still available for anybody seriously interested in good pond keeping. So many pond problems are created by the misuse and mistype of food. I would recommend that readers of this magazine consider reading this article and start to use the free calculator ... here's the link to a web address http://www.practical-water-gardens.com/koifood.htm where you can read the article and get the link to the calculator. You will save money and have better water quality at the same time.

7) Are there things you can do to improve their environment, such as water changes, filter cleaning, and so forth?

Most koi ponds do not have bottom drains which means debris collects on the bottom of the pond. The source of the debris is wind-borne material, uneaten food and food waste excreted by Koi as part of their normal metabolism. If the amount of debris is allowed to become significant then anaerobic (no oxygen) conditions build up in areas within the sunken debris. The bacteria that work in such anaerobic environments are generally not conducive to good pond keeping and fish health.

Consequently anaerobic conditions must be seriously avoided. This is one of the basic ideas behind adding a bottom drain to a pond and using vortex filters to aid the removal of solids. The problems associated with solids build-up apply just as much to bio filters many of which have dead areas that become stagnant and cause a myriad of undesirable problems.

Koi ponds and filter systems will work at their optimum in well oxygenated environments and every koi keeper should strive to improve the oxygen content of the water and the accessibility of this oxygen to filter bacteria especially.

All ponds (without bottom drains) and all biofilters should be thoroughly cleaned out using pond water as much as possible at least once per year and the best time is late autumn. Refill the pond with as much preserved old water as possible.

The secret to the effectiveness of most Japanese Matting and Vortex filter systems is actually quite simple ... and it is not the Japanese Matting per se. The design of such a system allows extremely intimate contact between the biomedia on which bacteria live (the matting) and the flowing water which is well aerated and agitated in close proximity to the matting.

This means the bacteria always have food and oxygen at their disposal and the metabolized nitrogen chemical are carried away from this interface. The vortex is good at removing solids so that the circulating solids do not block up the matting pores in which the bacteria are held.

The recent arrival of Kaldnes based filters work on exactly the same principle ... it is not the Kaldnes that is the sole reason for success it is the complete highly-aerated system fulfilling all the requirements of a dynamic aerobic bacterial system that is there to purify pond water. I would therefore recommend any koi keeper to strive to always get as much aeration and agitation around the filter medium as possible. This alone will prevent many stress problems at all time of the year.

There is no significant advantage in using Japanese Matting or Kaldnes unless aeration principles are applied as described. So no pond keeper should be tempted to just replace one static filter medium with either of these. They are great biomedia but only in the correctly engineered systems.

8) Can pond cleaning actually release dangerous bacteria into the pond?

If so, how do you do it safely? If there is a large amount of accumulated debris on the bottom of a pond then it is probable that much of this is organic and if disturbed in a pond there will be a tendency for the oxygen dissolved in the pond water to be depleted ... it will be taken up by bacteria that want to convert these solid organic wastes into carbon dioxide.

This is the most dangerous thing that can happen in my experience since low oxygen levels are potentially dangerous to everything in the pond. In addition anaerobic bacteria will be released and will have a short time to possible cause some problems but they will not live long in aerated water. Use of an efficient pond vacuum is highly recommended in these circumstances since the debris is sucked up gently without dispersing muck throughout the pond. In ponds with no bottom drains there is an excellent UK product which, when added to pond water, will do the "muck" digestion job on an ongoing basis. I would recommend interested readers learn more about the product which has been thoroughly tested and reported on in the UK. See my website Ponds and Blanketweed Solutions The same product is the only one that I can truly recommend as a blanket weed beater.

9) What is the biggest mistake people make when getting their koi ready for warmer weather.

When the water in the pond starts to warm Koi will start to swim around ... this means they are looking for food. Many pond keepers will immediately overfeed their fish not realising the fact that the biofilter is not yet working efficiently and that ammonia spikes will occur and remain for longish periods.

There should never be a detectable ammonia level in any pond let alone one that perseveres. This is probably the biggest mistake made in preparing for warmer weather. Consequently small amounts of high quality food as discussed above should be fed. The pond keeper should be meticulous to remove uneaten food. A second mistake is deciding to clean the pond out and the filter out and starting all afresh with tap water. Such cleaning is unnecessary and highly stressful to the fish in the pond.

A pond coming out of winter is unstable. Making significant changes to the pond environment by adding chemicals, bactericides, and so on adds to the instability so any changes must be done gradually and in small amounts and only for good reasons ... the consequences of which are fully understood. For example pond keepers should be aware of testing pond water and making judgements based upon a single test (rather than a history of test results plotted on a graph for example). Often the results will be quite wrong and in any case without a history the normal test values for a pond are not known. There is no perfect level for pH for example. Based upon testing there may be a temptation to add something to a pond and this can often be the very worst thing to do in an unstable pond environment.

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Useful Links for Important Equipment

Large biofilters and UVC ... http://www.practical-water-gardens.com/aquabead_pond_filters.htm

Smaller Biofilters and UVC ... http://www.practical-water-gardens.com/filterselect.htm

Pumps ... http://www.practical-water-gardens.com/pumpselect.htm

You'll see links on my web pages to UK and USA suppliers I trust and recommend.

USA online plant purchasing ... http://www.jdoqocy.com/click-1430060-437863

UK online plant purchasing ... http://www.bradshawsdirect.co.uk/BradshawsSite/pages/home/default.asp?AffiliateCode=BRAD07

Learn about Tony Roocroft's downloadable best-selling water gardening books ... http://www.practical-water-gardens.com/pondprofessor.htm You will find a link on this page to go to the store if you wish to buy a book.

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