Work

Optimization of fish feed formulation and pH regulation in on-demand coupled aquaponic systems: A model-based framework for sustainable nutrient and water management

Year: 2026

Type: article

Abstract: On-demand coupled aquaponic systems integrate recirculating aquaculture systems (RAS) with hydroponics, unidirectionally reusing nutrient-rich RAS effluent water for plant production. This integration reduces wastewater discharge, freshwater demand, and external fertilizer use. However, efficient operation requires the RAS effluent nutrient composition to align with plant nutrient demands, which remains a key challenge. To address this, we develop a flexible and adaptable optimization framework that balances the quantity of all obligatory nutrient inputs (feed, makeup water, bases/acids) to achieve a desired dissolved nutrient profile at the RAS-hydroponic interface by harmonizing fish feed formulation, the consequent nutrient excretion by fish, pH regulation via bases and acids, as well as water exchange volume and composition of intake water.The framework is tested across multiple scenarios, demonstrating its flexibility under varying operational conditions and the ability to balance competing goals, including nutrient solution optimization and reduction of carbon footprint and economic costs, while highlighting the trade-offs between these objectives. Additionally, results indicate that bases added in the RAS, namely potassium hydroxide (KOH), calcium hydroxide (Ca(OH)2), and magnesium hydroxide (Mg(OH)2), provide substantial amounts of dissolved K+, Ca2+, and Mg2+. Feeds rich in K and Mg or hard tap water used as makeup water cause concentrations to greatly exceed reference levels, defined here as the standard Hoagland nutrient solution. The most favorable conditions for approximating this reference solution arise when using soft or condensate water and feed low in K and Mg, but rich in phosphorus (P).

Source: Computers and Electronics in Agriculture

DOI: 10.1016/j.compag.2026.112358

Authors: Patrick Nestler, Christopher Shaw, Werner Kloas, Stefan Streif

Institutions: Chemnitz University of Technology, Leibniz Institute of Freshwater Ecology and Inland Fisheries, Humboldt-Universität zu Berlin, Fraunhofer Institute for Molecular Biology and Applied Ecology

Language: English

Topic: Innovations in Aquaponics and Hydroponics Systems

Subfield: Aquatic Science

Field: Agricultural and Biological Sciences

Domain: Life Sciences

SDGs: Responsible consumption and production, Zero hunger, Clean water and sanitation

Open Access status: hybrid

Estimated APC paid: $3,870