Recommended oxygen content: 8 mg/ at 25 C

Oxygen is the elixir of life for all organisms in the aquarium. Fish, slugs, corals, bivalves etc. need oxygen to breathe. But also the invisible helpers in the aquarium and pond, the pollutant-destroying bacteria, depend on sufficient supplies of oxygen in order to be able to carry out their useful activities. Just as on our earth, the supply of oxygen in the aquarium and pond is guaranteed by the assimilation activities of plant organisms (algae and higher plants). Oxygen supply can only be maintained by water movement and/or aerating with the appropriate technical equipment (from specialist pet suppliers) in those aquariums and ponds where sufficient oxygen cannot be supplied by plants, such as marine aquariums or aquariums stocked with plant-eating fish etc.
The following levels are recommended: Towards the end of the lighting period in freshwater aquariums with plants, the oxygen level from the activities of the plants, (without technical assistance e.g. aeration, but supported by moderate water movement), should correspond at least to the equilibrium level appropriate for that particular temperature. At 25 C the recommended level is approx. 8 mg/l.