Home - Moving koi - Important considerations and actions.
Quarantine. There is no doubt that many of you have heard it all before. Perhaps understanding its importance you already practice it to the full when purchasing new fish. Others may be less familiar and perhaps do not fully understand the reasons for quarantining and the consequences of not doing so.
Within the hobby of koi keeping there are many certain facts. One fact sure to catch up with you one way or another relates to the potentially destructive consequences of introducing new fish to your pond without either, a comprehensive quarantine regime, or an absolute trust in the source of the fish. Even in the latter case consideration should still be made to the stressed state of the fish due to a change in its environment. The potential affect of moving a fish from one environment to another is just as important as a consideration that the fish may be carrying some disease and it is one of the primary considerations of this article. Even the healthiest of fish need to be monitored to see how they cope with a move. People say that one of the greatest stresses in life is moving house. Well, this also holds true for koi. Indeed if you are looking for another analogy, one can say that if you have lived somewhere for a long time it might be harder to adjust to somewhere new, because you had got so used to your surroundings. If you are older, that can also add to the difficulty. Again all this is so true for koi. Any fish which has become established in a pond environment for many years is likely to have difficulty adjusting to new pond water and indeed if special consideration and monitoring is not given, a completely healthy fish can die simply through stress induced by a change of environment. Young fish or those that have not had time to become established in specific pond water will suffer the least stress during a move.
So, what is the issue here? It is simply about water chemistry, which is the combination of the chemical species dissolved in the water and in addition, the temperature of the water. The chemistry of the water of a particular area of a country is determined by two major influences. Firstly, its route to the under ground water table and secondly the production of waste products of fish metabolism and other pond life, including bacteria and others microorganisms. In addition, water chemistry can be temporarily affected by rainfall carrying pollutants and general acidity. Regarding its route to the water table, rainwater soaks into the surface of the earth and percolates down through underlying soil and rocks where it picks up minerals and salts. These minerals and salts give the water its chemical characteristics that vary according to the type of soil and rock that the water has trickled through. For example, water trickling through rock with a high granite composition will be slightly acidic and soft. This is because granite is a rock that is impermeable to water hence, few salts dissolve into the water to alter its composition. Hard water is generated by passage through highly water permeable chalk, limestone or gypsum. In this case water has a higher dissolved solids composition and is particularly high in calcium and magnesium salts.
With regard to keeping koi, hard water offers the advantage of being a good buffer. What this means is that sudden changes in the pH of the water are prevented when acidic or alkaline components are introduced resulting in a more constant environment for the fish. In addition, because of the high dissolved solids composition of hard water the osmotic pressure on koi is reduced. Osmoregulation is a term used to describe how a fish regulates the amount of water and salts entering its body. The physiological state of a fish's body must remain relatively constant regardless of its environment. Certain salts are dissolved in the fluids of the fish and each is at a particular concentration. The maintenance of these specific concentrations is a requirement for health and ultimately life.
So what is osmotic pressure? In simple terms it refers to the degree of pressure for water to enter the fish's body. Osmosis itself refers to the movement of water from a weak to a concentrated environment through what is known as a semi permeable membrane, which is effectively the fish's body. The fish's body contains a high concentration of dissolved salts at specific concentrations, hence water constantly wants enter to dilute the concentration. If this were left unregulated, the fish would simply continue to puff up and absorb water with obvious consequences. A fish suffering with defective osmoregulation shows the classic symptoms of dropsy.
As well as the movement of water, salts can also be lost from the body by a process known as diffusion. It is clear to see that the composition of water will influence the osmoregulation of the fish, hence a fish moving from water containing a high degree of salts to water with a lower amounts of dissolved solids or vice versa may need time to adjust. Of course it is not just about the mineral and salt composition of the water, which can vary dramatically even between hard waters, but also about the pH and the temperature of the water. Sudden changes in either of these important parameters can have profound effects on the physiology of the fish. It is always important to make adjustments of pH and temperature slowly to allow the metabolic processes of the fish to adjust. This is not a comprehensive review of how changes in water chemistry influence the physiological processes in koi, but this article serves to highlight the important elements.
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Collapsible vat, available up to 900 gallons |
So what are the consequences of a sudden change of environment particularly with regard to an 'established' fish ? It is a combination of events collectively known as stress. How stress affects a koi is determined by a number of factors. How severe is the stress ? How long has the koi been exposed to the stress inducing factor? What was the state of the health of the koi prior to stress ? What is the koi's reproductive status and what is its age ? Stress effects are cumulative, hence poor netting and handling of the fish prior to transport will increase the overall stress of the move. Short term stress results in the production of the fight or flight hormone adrenaline. You are probably familiar with this effect if you have ever felt in danger or become shocked for whatever reason. Some examples of the result are an increase in heart rate and release of glucose into the blood stream. In fish this also leads to increased gill perfusion to obtain more oxygen, leading to greater exposure of the gill surface to the water and hence, increased entry of water through the gills, bringing us back to osmoregulation. If a koi is continually exposed to stress by, for instance, a sudden and prolonged change of environment the hormone cortisol is also released. This release can lead to the loss of ions and salts from the gut. The positive effect of cortisol is from the supply of energy (mainly glucose) that helps the fish survive the stress. Unfortunately however, continuous exposure results in suppression of the immune system leading to greater susceptibility to disease and parasitic attack. For further information about stress in koi, please visit the Koi Oriental Veterinary Support page . An article on the subject is part of the recommended reading list from our supporting veterinary surgeon Chris Walster.
So, how can we help? Well, in an ideal world we wouldn't move koi once they have been established in a pond. However, hobbyists often want to move fish, be it to make space in a crowded pond or to upgrade their collection. Koi Oriental provides the Confidential Private Koi Sales section to meet this demand. We now need to bring back the familiar term quarantine. Quarantining a fish in a separate tank (minimum volume 300-500 gallons, approximately 1,300-2,200 litres) from the main pond will allow you to assess the welfare of the fish, both for the benefit of the new fish (how is it handling the move?) and for the benefit of your main pond's occupants (what latent or obvious diseases might it be carrying?). With regard to effects on the koi's osmoregulation, adding salt to its environment will reduce the osmotic pressure by increasing the dissolved solids in the water. If required, salt should be added to a concentration of 0.3%, 3g of salt per litre of water as a means of assisting the settling in period.
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Fibreglass freestanding tank suitable for quarantine use. Available up to 600 gallons |
The following is a list of ideal quarantine procedures.
Prepare a separate tank containing dechlorinated water. In the case of a very stressed fish consider adding 0.3% salt. Even better use water from the main pond. Ensure that a mature filter is available prior to adding the koi. Do not allow the fish to be exposed to ammonia or nitrite even for a short period at low concentration. Ensure adequate aeration in the form of an air pump. Heat the tank to minimum of 75oF, 24oC. One or two 300watt aquarium heaters are adequate for this job up to a volume of approximately 500 gallons. An immediate increase in the environmental temperature of a koi of around 5oC is perfectly acceptable, however, decreases in the environmental temperature should be no more than 2oC every 24 hours. Adjust accordingly to the desired temperature.
Pick up your fish. Ensure that it is properly netted and bowled to minimise stress and then adequately bagged (double bagged to prevent leaks). Ensure that there is adequate oxygen available for the journey. Place the fish in a cardboard box and when placing it in a vehicle ensure the fish is positioned sideways, i.e. head pointing to the side of the vehicle not front or back.
On arrival empty the fish and water into a bowl (add extra water if required). Inspect the fish for damage in transit and for general well being. Take a skin scrape and examine under a microscope for parasites. Transfer the fish to the quarantine tank using a koi sock, do not transfer the water in the bowl. It is advisable to cover the tank as some koi have a tendency to jump when moved, particularly to a much smaller volume of water.
Monitor the fish for a minimum period of 4 weeks.
Treat for any parasites that are found.
Ensure regular water changes through the quarantine period (minimum 10% per week)
Do not use any main pond equipment for your quarantine tank. You must have separate nets and bowls. Ensure that you wash your hands after handling a fish in quarantine or when you have come into contact with quarantine water.
For information about how to treat koi parasites or for information regarding koi health, please visit the Koi Oriental, Koi Appreciation, Development and Health, advice line which supports photo upload to assist your enquiry. In addition, visit the Koi Oriental Veterinary Support page.
Copyright Koi Oriental Limited 2005.
