Diseases of Koi fish – Angela Beckx

There are infectious and non-infectious diseases that effect Koi. Both infectious and non-infectious diseases can lead to fatalities in your Koi pond if you do not sort out the problem. In this article I will discuss the non-infections disease and in the next article I will discuss the infectious diseases.
Non-infectious diseases:
Oxygen depletion- Koi fish will hang near the surface of the water and gasp. They gasp at the surface of the water to try and get all the oxygen from the surface of the water over their gills. The reason why the Koi gasp can be due to there being to many Koi in the pond i.e. overstocking the pond. There maybe too much rotting algae in the pond and this leads to bad water conditions. If you have had a power failer and the temperature has being very hot the Koi will be under a lot of stress due to the lack of oxygen. If your power does fail, go to the pond with a bucket and lift up the water and add oxygen to the water. If the power has being off for quite a while you will need to change part of the water and use your hosepipe and spray the water into the pond to add as much oxygen and movement to the water, and remember to use a dechlorination product to remove chlorine and chloramines. Sometimes your Koi will be fine in your pond for years, but as they grow and get larger they require more oxygen and you may need to put in an air pump to supplement your filtration system. If you feel that your Koi look a bit lethargic or sluggish it maybe that they are not getting enough oxygen. It is a good idea to buy an air pump and add it to the Koi pond. A good air pump is an electric magnetic air pump made by Resun and it allows you to place a number of airs stone into the pond. They come in different sizes and are not too expensive but will make your Koi a lot happier.
Ammonia toxicity- Ammonia levels can rise quite rapidly in Koi ponds that are not filtered. They also can rise in ponds that are filtered but the filtration is insufficient for the size of the pond and the number of Koi living in the pond. What is important is that you must remember that ammonia is invisible and the water may look good to the eye, but when tested the ammonia level is actually dangerously high. In some cases you may notice cloudy water and a faint bad smell coming from the pond. This is when the ammonia level is very high and you need to change about 60% of the water. Unfortunately if your ammonia level was very high your Koi may die for a few days after you have corrected your ammonia level. This is due to gill damage the ammonia would of caused on the Koi.
Nitrite poisoning – If Koi suffer from Nitrite poisoning you can sometimes inspect the gills of the Koi and you may see that they are brown in colour. This is due to the change of hemoglobin to methaemoglobin in the blood. The cause of nitrite poisoning is from the incomplete bacterial break down of ammonia to nitrate by the bio filter. If there is not enough oxygen being supplied to the filter it may prevent the bacterial break down of nitrite to safer nitrate in the bio filter.
Gas bubble diseases – If you see that the water out of your tap is milky in colour which then clears within minutes is may be because the water is supersaturated with nitrogen. If fish are exposed to this water the dissolved nitrogen enters the bloodstream where it is gradually released from solution. Fish affected with gas bubble diseases often swim strangely before dying. If fish are held up to the light small air bubbles can be seen between the rays of the fins. If you see your water looks milky, leave it to stand for about one hour and aerate it.
Low Ph- If your ph drops below 6.5 often your fish will stop eating and sit on the bottom of the pond and look lethargic. If you notice this you must correct your ph to 7.2-8.5 to prevent fatalities. To correct your ph add bicarb of soda to the pond, for the correct dose to use contact your Koi dealer.

Angela Beckx
Koi @ Jungle
031-2098781