Sustainable off-grid cage culture: assessing the performance of a functional, energy-autonomous, solar-powered farming model for Etroplus suratensis (Bloch, 1790) in remote mangrove habitats

Sustainable aquaculture in remote mangrove habitats is often constrained by the lack of reliable grid electricity, limiting critical operations such as aeration and real-time monitoring. This study evaluates the performance of a functional, energy-autonomous, solar-powered cage culture system for Etroplus suratensis established in a remote mangrove site at Nedungolam, Kollam district, Keralam, India. A 3 kW (12 kWh day −1 ) photovoltaic system was deployed to support aeration, lighting, surveillance, and wireless monitoring, with an average energy consumption of 5.7 kWh day −1 . Fingerlings (4.19 ± 0.81 g; 5.89 ± 0.81 cm) were stocked at a density of 50 fish m −3 in nine HDPE floating cages (10 m 3 each) and reared under semi-intensive conditions for 7 months. Feeding rates were adjusted from 3 to 5% to 7–9% of biomass as growth progressed. Significant improvements ( p ≤ 0.05) were observed in key water quality and sediment parameters in the solar-aerated system, including dissolved oxygen, nutrient dynamics, plankton abundance, and sediment redox potential. At harvest, fish attained an average weight of 205.07 ± 1.25 g, yielding 80.5 ± 1.09 kg per cage (8.05 kg m −3 ). The total system installation cost was Rs. 6,09,386 (~6816 USD). The results demonstrate that solar-powered, off-grid cage culture is a technically feasible and environmentally sustainable approach for aquaculture in energy-deficient mangrove ecosystems, effectively mitigating nocturnal oxygen stress while enabling autonomous farm operation.