Cascade and Vertical Aeration Systems in Aquaculture: Current Status, Design Hypotheses and Future Needs

Aquaculture being one of the fastest growing food production sectors still possesses a significant challenge for maintaining optimal dissolved oxygen (DO) levels in farmed ponds particularly in intensive culture systems. Many times, the oxygen demand of the cultured organisms is not met by the natural aeration processes. Hence, the artificial aeration comes into play to support health, growth and productivity of the cultured organisms. Aeration methods like stepped cascades, perforated trays and shower systems have been studied for their ability to improve oxygen transfer by increasing air and water interaction. Cascade aerators are noted for their simplicity and low cost, making them ideal for small-scale farmers, however shower aeration systems show better performance than cascade aerators due to geometric optimization of designs. This review primarily discusses about the importance of cascade aerators and vertical aeration systems used in aquaculture practices highlighting the principle, design, efficiency and their further improvements suiting to the aquaculture practices. Though having a brief progress in research, there are still lack of understanding about the design performance, cost-effectiveness and practical feasibility of these systems under different pond aquaculture conditions. Comparative analysis of reported Standard Aeration Efficiency (SAE) (≈1.2-4.98 kg O₂/kWh) and Standard Oxygen Transfer Rate (SOTR) values among different cascade aerators, alongside case studies from wastewater and aquaculture applications, is used to identify factors governing aeration efficiency, scale limitations and field-level constraints. Building on these insights, the study discusses the development and pond-scale testing of AICRP on PEASEM, centre at ICAR-CIFA vertical aeration prototypes: cascade aerators and shower-based towers, that achieved 33-40% increase in pond DO and demonstrated their suitability for aerating 0.12 ha ponds with relatively low capital cost. The review contributes an integrated conceptual framework for next-generation vertical aeration towers that combine cascade and shower principles, enable continuous water recirculation and can be coupled with solar power and sensor-based automation to minimize energy use while maintaining optimal DO. By explicitly addressing the challenges of energy efficiency, design optimization, scalability and real-pond validation, this work outlines a pathway for replacing or complementing conventional mechanical aeration with cost-effective, environmentally sustainable gravity-driven systems in intensive aquaculture.