In the present study, an improvised design over circular stepped cascade (CSC) and pooled circular stepped cascade (PCSC) aerator, named the perforated pooled circular stepped cascade (PPCSC) aerator, has been conceptualized and tested for its suitability as an aerator for small intensive aquaculture ponds. Based on dimensional analysis, dimensionless geometric parameters – ratio of width of consecutive steps (Wi/Wi+1) and ratio of perforation diameter to bottom-most radius (d/Rb) and dimensionless dynamic parameters – Froude (Fr) and Reynolds (Re) number were proposed. Initially, aeration experiments were conducted to optimize the geometric parameters, keeping the dynamic parameters constant. Keeping the optimized values of Wi/Wi+1 = 1.05 and d/Rb = 0.0027 as constants, aeration experiments were further conducted at different discharges (Q) and different bottommost radius (Rb) to study the characteristics of oxygen transfer and power consumption of PPCSC aerator at different dynamic conditions. Based on the optimized results, four prototype PPCSC aerators with Rb = 0.75 m, 0.90 m, 1.05 m and 1.20 m were fabricated for their aeration performances. The results showed that the standard aeration efficiency (SAE) values of the prototype PPCSC aerators based on brake power ranged between 3.36 and 4.98 kg O2/kWh, with the average being 4.45 ± 0.741 kg O2/kWh. This shows that the SAE of the PPCSC aerator is many more folds higher than that of the other available cascade aerators, viz., PCSC (SAE: 2.873 ± 0.342 kg O2/kWh) and CSC (2.470 ± 0.256 kg O2/kWh) aerators. The study clearly indicates that this PPCSC aerator may very well be used as pre-aeration or post-aeration units in water or wastewater treatment plants and small-scale intensive aquacultural ponds, replacing the other existing aerators.

Organic aquaculture is a new approach in the modern farming system. As the capital investment is higher for setting up the organic aquaculture, it is essential to conduct an economic feasibility study with compare the conventional farming system. In the current study, economic feasibility of culturing Indian major carps (IMC) using conventional culture system and organic culture system (OCS) were evaluated. IMC was cultured for three consecutive years from 2017 to 2019 in experimental ponds of 0.015 hectare (ha) area each. The crude protein content of the organic and conventional feed was maintained at the same iso-nitrogenous level (32% crude protein) but the highest production to the tune of 19 tons per ha was obtained in OCS. Further, in case of OCS, apart from fish production, vermicomposting to the tune of 45,000 kg ha⁻¹ in the first year, and 90,000 kg ha⁻¹ from second year onward is achievable by installing a vermicomposting unit of 200 tons annual capacity. Economic analysis of the culture systems assuming a project period of 10 years showed that the highest net present value (NPV) of 1.06 million USD, a payback period of one year and nine months and an internal rate of return (IRR) of 51% are achievable per ha of fish culture pond for OCS. Sensitivity analysis of various costs performed for OCS revealed that profitability of the organic fish farming investment is most sensitive to the total fish production and sale price of the organic fishes. In terms of production of fish and economics of organic culture system is proved to be the best available technique.

The aquaculture industry will be crucial in helping the world’s food supply and keep up with the demand. Aquaculture, like agriculture, must expand and develop sustainably in all the countries to keep up with the rising demand for food. To this end, the aquaculture industry has forged new scientific and technological frontiers in pursuit of long‐term food security. Among these is organic aquaculture, whose distinctive protocol has great potential to advance aquaculture. Organic aquaculture is being explored for multiple reasons, encompassing the aim to minimize environmental footprints, fulfill escalating consumer appetites for seafood, and contend within the industry this paper endeavors to address the gaps in current literature by offering an exhaustive overview of various aspects of organic aquaculture. This encompasses its regulation, production methods, food quality, environmental impact, economic viability, as well as socioeconomic and marketing aspects. It is necessary to acquire more knowledge about organic farming techniques before switching over to organic aquaculture on a large scale. Organic regulation, production, food quality, economic performance, and social and marketing issues are at the top. This review found that consumers lack understanding of organic principles, and regulations are inconsistently applied. However, organic aquaculture promotes social equality by protecting producers’ rights to work without discrimination based on gender, race, or sexual orientation factors that ultimately boost the industry’s popularity. Organic aquaculture viability varies depending on factors like feed costs, fixed expenses, and the premium pricing sensitivity, making it unfeasible for certain species. However, from both societal and economic standpoints, organic aquaculture appears most suitable for implementation in developing nations.