In intensive aquaculture systems oxygen supplementation is necessary to prevent hypoxia; however, oversupply can hyper-saturate systems causing gas bubble disease. Oxygenation in aquaculture, fish holding and transport systems using standard technologies is extremely inefficient; standard oxygen transfer efficiencies (SOTE) are estimated at between 2 and 6% per m submergence for coarse and fine bubble diffusers, respectively, at standard conditions of 0 ppt salinity and 20 °C. Advances in the efficiency of gas–liquid phase processes has seen the emergence of nanobubble technologies producing ultrafine bubbles (⌀ 1 µm). The advantage of nanobubbles over larger micro/macrobubbles is that they are neutrally buoyant, negatively charged and can remain within the water column, potentially for weeks. Nanobubble technologies now have a demonstrated application across a broad variety of industries including wastewater treatment, biomedical engineering, gas and oil industry, agriculture, and the food industry. Surprisingly, outside of Japan, there has been little research on the application of nanobubble technology to the aquaculture sector. Nanobubble technology can potentially improve oxygen delivery systems for fish stock and water treatment in aquaculture systems, improving the nitrifying capacity of biofilters and efficiencies in fractionation units. However, there are currently no reliable studies demonstrating the efficacy of nanobubble technology, nor any assessment of the potential health impacts on fish in aquaculture systems. We have undertaken a preliminary pilot trial with encouraging results. Oxygenation was applied to a recirculating aquaculture system via nanobubble injectors for 10 days and fish (yellowtail kingfish) were observed to feed and behave normally when compared to a control group. Before this technology can be considered for broader adoption, a thorough long term investigation needs to be undertaken to assess the long term health effects on fish stock held in nanobubble oxygenated water and the suitability for application of this technology to the aquaculture industry.
