The effects on the antioxidant status and immune responses of Largemouth Bass Micropterus salmoides in an aquaponic system with Ocimum basilicum var. pilosum

ABSTRACT. Aquaponics is a novel ecological farming model integrating aquaculture with hydroponics. Hairy basil, a medicinal edible plant, was suitable for establishing an aquaponic system. However, the effects of hairy basil on water quality and fish immunity were unclear. This present study aims to investigate the effects of hairy basil ( Ocimum basilicum var. pilosum ) on non-specific immunity in largemouth bass ( Micropterus salmoides ) and aquaculture water in an aquaponic system. Immune and antioxidant parameters were assessed following Aeromonas hydrophila challenge. The results showed that aquaponics based on hairy basil floating beds significantly reduced the level of NH₄⁺-N and NO₂⁻-N over 105 days. Hairy basil activates non-specific immunity of largemouth bass by increasing anti-inflammatory ( IL-10, TGF-β, IL-21 ) and antibacterial genes ( Lys-g, Defbl2 ) in intestines and head kidneys during A.hydrophila infection. The upregulation of IL-22, a cytokine known for its role in tissue protection and barrier defense, suggests an enhanced intestinal mucosal immunity in fish from the aquaponics system. Meanwhile, TNF-α , a key pro-inflammatory cytokine, showed no significant alteration. Concurrently, the activities of acid phosphatase (ACP), alkaline phosphatase (AKP), lysozyme (LYS), and total antioxidant capacity (T-AOC) in serum were higher than those in the control system. Moreover, aquaponics significantly reduced intestinal damage and death rates caused by A.hydrophila . Our data demonstrated that the aquaponics with hairy basil contributes to enhancing the health and disease resistance of largemouth bass, which provides a theoretical foundation for ecological agricultural model.