Physiological Stress, Yield, and N and P Use Efficiency in an Intensive Tomato–Tilapia Aquaponic System

Accelerated population growth has driven the search for efficient food production systems such as aquaponics, which integrates aquaculture and hydroponics in a closed-loop configuration. In conventional aquaculture and hydroponic systems, intensification often causes physiological stress, nutrient imbalances, and resource inefficiencies. This study tested the hypothesis that, in an intensive aquaponic configuration, the synergy between aquaculture and hydroponic modules helps mitigate stress, improve nutrient and water use efficiency, and sustain overall performance compared to stand-alone hydroponic and aquaculture systems. The experiment was conducted under greenhouse conditions over three consecutive 180-day cycles, comparing an intensive aquaponic system with aquaculture and hydroponic modules. Tilapia in aquaponics showed 30% lower cortisol and 22% lower glucose (p < 0.05) than in aquaculture, indicating reduced stress. Tomatoes showed 25% higher catalase activity and 18% higher phenolic content (p < 0.05), reflecting moderate oxidative stress. Tilapia productivity reached 38.4 kg m−3 (+11.7%), tomato yield was 22.7% lower than in hydroponic conditions, and N–P use efficiencies were 23.3% and 20.7% (p < 0.05). Water use efficiency improved by 17.4%. Despite reduced plant growth, aquaponics decreased fish stress and enhanced nutrient recovery, supporting its potential as a sustainable, resource-efficient alternative for integrated food production under intensive conditions.