Autorin: Dr Sabine Özgönül-Wagner
Isn't that a nice idea? A warm summer evening, the crickets are chirping and you're sitting by your pond with a good glass of wine in your hand, watching your beloved koi jumping.... Why do koi jump out of the water?
What's wrong with this picture? Exactly, there are no trout in the pond - jumping for insects is part of their normal behaviour - but it is a KOI pond. Carp do not jump! At least not when they are doing well. So why do these beloved animals jump? If you take the time, you can usually observe in such ponds that the animals rub themselves against folds in the liner, plant baskets, bottom drain covers or whatever else is available. On closer inspection, some may even have recognisable rub marks or even injuries on their gill covers or flanks.
What causes this behaviour? There are many reasons for this and even an expert cannot say what the cause is just by looking at the way the animals jump or rub themselves. A detailed examination is usually required. I would like to explain the most common reasons for rubbing and jumping here.
Parasiten
By far the most common cause of jumping and rubbing. Fish do not have hands to scratch themselves. However, parasites such as skin and gill worms, Costia, Trichodina and Ichthyophthirius multifiliis (to name just the most common) cause itching. What do the poor animals do then? They rub themselves on every nook and cranny in the pond that they can find and sometimes jump out of the water in desperation. After examining skin and gill swabs, targeted treatment can be initiated. For environmental and animal welfare reasons, treatment should only ever be targeted!
Water quality
Fish are much more dependent on their surrounding environment, the water, and much more strongly influenced by it than we land creatures. If it "stinks" we ventilate or, if possible, simply leave the unpleasant area. Fish can do neither. In some ponds, fish seem to become so desperate that they try to save themselves by jumping out of the water. For example, I personally once examined a pond that had a pH of 3 (!!!), which means that the pH value was closer to that of stomach acid than to the neutral point. Water is a difficult habitat for us humans to understand. Clear water does not mean good water and muddy water does not mean bad water. Regular testing of the most important water values such as hardness, pH, ammonium/ammonia, nitrite and above all the oxygen content using suitable test methods should be a matter of course for koi enthusiasts, as should regular partial water changes at the height of summer.
Increased bacterial pressure in the water can also cause rubbing and jumping. All pipes and filter chambers must therefore also be regularly cleaned of excessive deposits as well as faeces and food residues.
Last but not least, the amount and type of food plays a decisive role in the water quality and gill health of the fish. But I will go into this in another article. You can find regulating pond bacteria here
Chemicals
Last but not least, various chemicals that have intentionally or unintentionally entered the pond can cause skin irritation, resulting in jumping and rubbing.
To summarise:
- Koi jumping is an indication that something is wrong
- The cause must be investigated and eliminated
- Please do not simply use medications or substances in the pond that are supposedly "egg-laying woolly mice" without having them tested. There is no such medication. Always determine the cause and tackle the problem specifically
- If necessary, check the filtration (including pipework) and feeding (in terms of quantity, freshness, etc.) before a specialist visits
