WWW.WAS.ORG • WORLD AQUACULTURE • MARCH 2026 65 solutions like sedimentation tanks and biofilters can improve or reduce ecological impacts. Some farms now use biofiltration systems based on algae or aquatic plants to absorb excess nutrients. These eco-friendly approaches can improve water quality while creating byproducts like fertilizer or biomass for feed. Incorporating algae and aquatic plants into culture systems plays a role in restoring balance. Species such as Chlorella and water lentils effectively remove dissolved nutrients, particularly nitrogen and phosphorus, which contribute to eutrophication. These natural filters convert waste into biomass that can later be processed as fertilizer or as a source of protein in aquafeed. Integrating these systems supports a circular economic approach. Many studies and reviews demonstrate this approach (Gao et al. 2016; Ahmadi and Dursun 2024). In aquaculture, a viable aquatic environment is often achieved through bio-filtration, the process by which beneficial bacteria convert toxic ammonia into less harmful nitrate. Maintenance of microbial balance is necessary for preserving good long-term water quality. Biofloc Technology (BFT), in this context, represents an innovative evolution of this principle, where instead of using distinct physical bio-filters, the system converts the entire water column into a living bio-filter. Adding carbon promotes the growth of microbial aggregates (floc) which directly consume ammonia from the water. This not only performs water purification but also converts pollutants into a protein biomass which can be consumed by fish or shrimp as a supplementary feed and thus combines filtration and nutrition functions for more efficiency and sustainability. Integrated Aquaculture Systems This is an important approach to sustainability that simulates natural ecosystems, where waste is not seen as a problem but as a useful resource feeding another part of the system. These linkages between diverse types of organisms ensure waste is treated while also reducing environmental impact. Aquaponics brings fish farming and hydroponics together. Water from fish tanks containing fish waste and feed residues (organic matter) flows to a plant growing unit, where plants absorb nutrients as fertilizer for growth. The filtered water is returned to the fish. This system simultaneously produces fish and crops, and it achieves very low water usage through constant recycling. Many farms worldwide now adopt this approach to minimize water usage. In Egypt, Al Haggag Farms, one of the country’s pioneers, has proved this system works for growing organic crops and using water wisely (Figure 1). Integrated Multi-Trophic Aquaculture (IMTA) combines different aquatic species that perform complementary biological functions. Fish produce nutrient-rich waste which seaweeds and algae use as fertilizer, while filter-feeding species, such as mussels and oysters, filter out suspended particulates and enhance water quality. This natural balance minimizes waste by producing valuable products from waste to improve water quality. Therefore, IMTA provides long-term ecological benefits while providing multiple products that increase the farmer’s income, demonstrating how healthy ecosystems can drive economic success. A successful IMTA example is the integrated aquaculture system implemented in southeastern China (Fujian and Guangdong provinces) where shrimp, oyster and rabbitfish are co cultured. Shrimp feed on artificial feed, while oysters thrive on plankton and the rabbitfish consume algae. Electricity consumption is much lower than in a traditional system, while organic discharge is non-existent, showing a clear model of economically efficient environmental sustainability. Building Human Capacity: Empowering Farmers and Women Sustainability is not just about environmental aspects, it is about people as well. Farmers need training and support to effectively adopt new practices. Across the Middle East and North Africa, WorldFish and other organizations are training local farmers and women in sustainable aquaculture practices. Moving Toward a Sustainable Future in Aquaculture The survival of aquaculture will depend on its ability to adapt to a changing global landscape, one defined by limited water, energy, and feed resources. This is not a choice but a requirement for the industry to maintain productivity and food security in the long term. By utilizing renewable energy, developing aquafeed, and improving waste management, the industry can close the loop and move closer to a fully realized circular economy (Figure 2). These practices not only mitigate environmental impacts but also help the whole industry thrive and enhance resilience and profitability for society. The future will belong to the farmers, researchers and innovators who consider their work in terms of sustainability. They will see every difficulty not as an obstacle but as a chance to rethink, redesign, or even rebuild the interaction between aquaculture and nature into a more balanced model. Aquaculture, if given proper management, may be the most effective approach for achieving food security for humanity in a resource-constrained global environment. Notes Yomna Elshamy, Aquaculture journalist and Faculty of Aquatic and Fisheries Sciences, KafrelSheikh University, KafrelSheikh 33516 Egypt. Email: yomnae834@gmail.com References Ahmadi, Abdul Wahed, and Sükrü Dursun. 2024. “Assessing the Efficiency and Role of Duckweed (Lemna Minor) in the Removal of Pollutants from Wastewater Treatment Plant Secondary Clarifier Tanks: A Comprehensive Review.” Central Asian Journal of Water Research 10 (March): 115–25. https://doi. org/10.29258/CAJWR/2024-R1.v10-1/115-125.eng Eilam, Yahav, Hamdan Khattib, Noam Pintel, and Dorit Avni. 2023. “Microalgae-Sustainable Source for Alternative Proteins and Functional Ingredients Promoting Gut and Liver Health.” Global Challenges 7 (5): 1–24. https://doi.org/10.1002/ gch2.202200177 Gao, Feng, Chen Li, Zhao-Hui Yang, Guang-Ming Zeng, LiJuan Feng, Jun-zhi Liu, Mei Liu, and Hui-wen Cai. 2016. “Continuous Microalgae Cultivation in Aquaculture Wastewater by a Membrane Photobioreactor for Biomass Production and (CONTINUED ON PAGE 79)
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