The contribution of Indian fish to the world's food basket has been substantial. India is the second-largest fish producing and second-largest aquaculture nation in the world. India has about 7516K of the total length of coastal line including Islands [21] and nearly 2 million sq Km of EEZ and half a million sq Km. of Continental Shelf. India has an estimated fisheries potential of 4.41 million tonnes from these marine resources. Similarly, we have 3.15 million hectares of reservoirs, 2.5 million hectares of ponds and tanks, 1.25 million hectares of brackish water area, cold water resources of hilly states, and all other inland fishery resources offer a production potential of about 15 million tonnes. Against this potential, Currently, fish output in India is estimated to be 13.4 million tonnes (MT), of which 32% comes from the marine sector and Mission Mariculture -2022 aimed at meeting the fish demand of 20MT by 2022-23 under Pradhan Mantri Matsya Sampada Yojana (PMMSY) supporting "Blue revolution." With its multi-dimensional activities, the Blue Revolution focuses mainly on increasing fisheries production and productivity from aquaculture and fisheries resources, both inland and marine, besides strengthening post-harvest fishery infrastructure facilities. This will also fulfill the gap to achieve the additional fish production of 5.0 million tonnes by the end of 2022. With the Mission Mariculture-2022, it is proposed to promote mariculture, including open sea cage culture in all maritime states and UTs, on a priority basis with the active participation of fishers. Hence it is necessary to develop various technologies on aquaculture to have sustainable fish production. One of the technologies is open sea cage farming through which the country can enhance the fish production only under the marine sector from the present contribution of 32% to 60%. If we met with an additional 18%-22% from the marine sector, India would become the world's most significant fish production. Open sea cage farming can be classified into open sea floating cage and open sea submerged cage systems. Though many cage technologies are available for both scenarios, the open sea submerged cage system, and its technologies shall be sustainable with high capacities of fish production in a single cage system, which minimizes both captive and recurrence costs. Till now, India has implemented open sea floating cages of various types of small and medium capacities which need more attention during bad weather and to the stage of hypoxia (Depletion of DO concentration in water), which results in more stress to fish to die due to non-availability of dissolved oxygen in seawater by the cover of algae formation near to the floating cages. Now, this is the stage where India can implement an open sea submerged cage system which gives more yield and sustainable aquaculture in the near future in a massive manner
