Osaka Gas Liquid started selling its oxygen aeration system for land-based fish farming on August 1. This system is being used in a pilot project at the Kindai University Aquaculture Research Institute. The system was displayed from August 21 to 23 at the Japan International Seafood & Technology Expo held at the Tokyo Big Site, the International Exhibition Center.
The system is called OXSERVE, and it is used to aerate land-based fish farming tanks with oxygen to increase the dissolved oxygen concentration and thereby promote growth of the fish. The system contains an oxygen supply section with a built-in PSA device, dissolved oxygen meter, circulation pump, and micro-bubble generating nozzle integrated into one unit. Because related equipment is provided in a single package, the system is compact and has a small installation footprint. Furthermore, the system operates on a 100-V power supply, so it can be installed near the tank, where space is generally limited.
The system also includes IoT functionality so that the user can check the dissolved oxygen concentration, oxygen flowrate, and water temperature from a computer or tablet merely by bearing the cost of communications. For example, the user can detect errors in the dissolved oxygen concentration and some other problems without going onsite and take suitable steps.
The company’s Industrial Gases Sales Division says, “Because oxygen is supplied from a PSA device, running costs are only about 1/7th in comparison with a system that uses gas cylinders. There is no need to replace cylinders, which enables efficient system operation. Currently the Kindai University Aquaculture Research Institute is performing a pilot project to farm flounder. The flounder are growing larger in comparison to flounder raised without the OXSERVE.”
In the project, two 7 t tanks are being used. In one of the tanks normal fish farming without the OXSERVE is being performed. In the other tank, the OXSERVE is used. Growth is given as the weight of flounder per square meter on the bottom of the tank. In comparison to 20 kg/m2 for normally raised flounder, the weight was 120 kg/m2 of flounder in the tank with the OXSERVE.
The pilot project was started in July 2023, but because of the high density of flounder that grew in the tank with the OXSERVE, one more tank was added in the spring of 2024 to separate them. The pilot project was continued with three tanks: the normal fish farming tank without the OXSERVE, the high-density tank with the OXSERVE, and the tank that was added with the flounder separated from the high-density tank to achieve the same growth environment as the normal tank (i.e., a flounder density of 20 kg/m2) but with the OXSERVE.
The pilot project was interrupted in July 2024 and sensory evaluations are scheduled for the flounder from all three tanks. A processing house in Toyama Prefecture is asked to cure some of the flounder between sheets of kelp. The sensory evaluations will be performed by 120 to 150 employees and their families of the company, as well as 120 students from Kindai University.
The first stage of the pilot project was completed, but the pilot project will continue. Of the three tanks, the two tanks with the OXSERVE will be consolidated into one tank and testing will be continued with a high-density tank with the OXSERVE and a tank with normal fish farming. The next stage of the pilot project will verify the impact of flounder growth in the second growing season.
The Industrial Gases Sales Division said, “When we showed a demonstration system of the OXSERVE at the Japan International Seafood & technology Expo in 2023, people involved in fish-farming eels, shellfish, shrimp, and other seafood were eager to talk to us. We want to expand beyond flounder and apply our system to other seafood.” The company’s sales target for this fiscal year is five systems.
The company has been marketing micro-bubble generating nozzles since 2016 as an industrial gas product. It was developed mainly for carbon dioxide baths in bathhouses, but in order to sell them for fish farming as well, the company asked the cooperation of the Kindai University Aquaculture Research Institute in 2021. Whereas the Institute had also been involved in flounder fish farming research, and the flounder harvest was high around Japan, the company started the flounder pilot project using the OXSERVE in cooperation with the Institute, hoping that the system could be adapted for other seafood in the future.