Dissolved Oxygen in your Koi Pond is important. Koi breathe by pumping water over their gills to extract essential oxygen, which is invisibly dissolved in the pond water.
Fortunately, compared to other fish species, Koi do not require an especially high level of dissolved oxygen (DO) which makes them relatively undemanding in this area. Even when, through whatever reason, DO does fall below a koi's minimum requirement, they can adapt by coming to the surface to gulp in air as a short-term survival strategy. However, this is extremely stressful for fish and if you are witness to such an extreme change in behavior the alarm bells should start ringing.
How Koi Respond to Oxygen Levels in Pond Water
Typical Koi Response
|3 ppm||Koi begin to die|
|5 ppm||Koi barely survive|
|7 ppm||Koi will live|
|8 ppm||Koi will do well|
|11 ppm||Koi do wonderfully|