This study evaluates the impact of recirculating aquaponic cultivation on the biochemical, mineral, and antioxidant profiles of Swiss chard (Beta vulgaris var. cicla) integrated with Nile tilapia (Oreochromis niloticus), which serves as a source of nutrients through metabolic waste transformation within the system. Water quality parameters and microbiological testing confirmed efficient nitrification and system safety, with no Escherichia coli detected. Results showed that aquaponic cultivation yields a high nutritional value of Swiss chard, yielding high crude protein (31.4% DW) and mineral-rich biomass (ash 22.8% DW). Substantial concentrations of essential elements were recorded, including Ca, Mg, Fe (253.7 mg/kg DW), Zn, and Cu, suggesting high ionic bioavailability in the recirculating system. Physiological stability was reflected by a chlorophyll a content of 4.74 mg/g DW. Furthermore, the plants exhibited a robust phytochemical profile, with total phenolics (4.13 mg GAE/g DW) and flavonoids (5.18 mg QE/g DW) driving strong antioxidant activity (93.1% ABTS inhibition). These findings demonstrate that integrated aquaponic systems function as effective nutrient bioreactors, supporting high plant functional quality while supporting sustainable food production. The results validate aquaponics as a viable, climate-smart strategy for high-quality leafy vegetable cultivation within a circular bioeconomy framework.

Aquaponics is an integrated and resource-efficient production system that combines aquaculture and hydroponics in a closed-loop environment with reduced water consumption and nutrient losses. The present study evaluated the nutritional composition, mineral profile, microbiological quality, and antioxidant-related phytochemical characteristics of red amaranth (Amaranthus cruentus L.) cultivated in a recirculating aquaponic system under controlled environmental conditions. Leaf biomass was analyzed for proximate composition, macro- and micronutrient content, total phenolic and flavonoid compounds, betalains, chlorophyll pigments, and antioxidant activity using standard analytical and spectrophotometric methods. The results demonstrated high crude protein content and substantial accumulation of essential minerals, particularly calcium, potassium, and magnesium. The analyzed biomass also exhibited elevated levels of phenolic compounds, flavonoids, betalains, and chlorophyll pigments associated with considerable antioxidant potential. The pigment profile suggested good physiological adaptation of plants to aquaponic cultivation conditions. In addition, microbiological analysis confirmed acceptable hygienic quality and safety of the harvested plant material. Overall, the findings indicate that red amaranth can be successfully cultivated in aquaponic systems while maintaining high nutritional value and functional food potential. The study highlights aquaponic cultivation as a sustainable approach to producing nutrient-dense leafy vegetables within environmentally responsible agricultural systems.