Recirculating Aquaponics System Enhances Bioactive Compounds in Tomato ( <i>Solanum lycopersicum</i> ) and Growth Performance of Asian Seabass ( <i>Lates calcarifer</i> ) in a Sustainable Food Production Model

Aquaponics represents a promising strategy for sustainable food production by integrating fish culture with plant cultivation in a shared recirculating water system. This study evaluated an integrated recirculating aquaponics system (RAS) combining tomato (Solanum lycopersicum) cultivation in media-bed hydroponics with the concurrent production of Asian seabass (Lates calcarifer), with the objectives of (i) assessing fish growth performance and feed utilization, (ii) determining the effects of RAS-derived nutrient inputs on tomato yield and bioactive compound content, and (iii) comparing these outcomes with a conventional hydroponic control. Over a 12-week production cycle, tomatoes grown in the RAS treatment exhibited significantly higher total phenolic content, tannin content, flavonoid content, and lycopene concentration compared to the hydroponic control (p < 0.05), alongside significantly greater DPPH and ABTS radical scavenging activity. Tomato fruit yield and vegetative growth parameters were also improved in the RAS treatment. Concurrently, L. calcarifer demonstrated satisfactory growth performance, with specific growth rate (SGR), feed conversion ratio (FCR), and condition factor (CF) values comparable to benchmarks reported in the literature for monoculture RAS systems. Water quality parameters remained within acceptable ranges throughout the experiment, and stress biomarker analysis indicated that the RAS environment did not impose excessive physiological stress on either the plants or the fish. These findings demonstrate that integrated RAS aquaponics simultaneously enhances the nutraceutical quality of tomato and supports efficient seabass production, offering a resource-efficient and climate-resilient model for sustainable food systems, particularly in water-scarce regions.