The importance of oxygen for your Koi fish.
Oxygen plays a very important role in keeping you koi health and happy. Often oxygen is not given the correct amount of attention from koi keepers.
Oxygen requirements for you koi differ according to the area in which you live and the temperature. The warmer your temperature and the higher your altitude will mean you need to supply your koi with more oxygen.
Koi require 6mg/l of oxygen in the water for good growth and health. To achieve this you need to make sure you have a good pump running into your biological filter as well as having a Venturi or air pump with multiple air stones leading into different areas of the pond. You should have your pump, sucking water from the one side of the pond and returning the water to the opposite side of the pond. This is to make sure you do not have any dead spots in your pond, where you may lack oxygen. Oxygen is used by a lot of living components in a koi pond. These components are: Koi fish, bacteria in the biological filter, plant life, organic matter as well as your undesired algae in your pond.
Often water plants are bought under the impression that they will give your fish oxygen. The plants use the carbon dioxide for photosynthesis and release oxygen back into the water in the day, but at night the process is reversed and plants compete for the available oxygen with your koi. This is why it is so important not to place your koi pumps on to timers, like a swimming pool pump as the oxygen levels become very low and you have very unhappy koi as well as a biological filtration system that does not run at full capacity as it is starved of oxygen.
Koi use up oxygen when they feed, when they spawn as well as when they are stressing and not well. As the water temperature rises in the pond, more oxygen is used as the fish become more active. That is why in summer you will get the best growth from your koi as they are more active and therefore eat more food. You can increase their food you give them and feed them 3 times a day if you are able to. As koi have a small stomach, it is best to feed them small amounts often, rather than a whole lot of food at one meal. You must remember to do regular maintenance of your mechanical and biological filters. This is to keep your organic matter to a minimum as oxygen is consumed when organic matter is decomposing.
Koi @ Jungle