Like humans, aquatic species need oxygen to survive. In aquaculture, the oxygen is dissolved in the body of water. Aquaculture farms can be more productive by increasing the number of aquatic species for a given water volume (also known as stocking density). However, as the number of aquatic species increases, the demand for oxygen increases as well. One way to increase the amount of dissolved oxygen is to aerate the body of water so that the oxygen from air can contact as much of the water as possible. The air/liquid contacting allows the atmospheric oxygen to dissolve in the water to replenish the oxygen used up by the aquatic species. However, the oxygen content in air is only 20.9%.