Efficacy of dietary Ceratonia silique and Zingiber offcinale on the immune-antioxidant-signaling pathways, growth, physiological response, and ammonia resistance in Oreochromis niloticus reared under unchanged water

Prioritizing water management and maintaining its quality for as long as possible, while lowering related stressors, are crucial for sustainable aquaculture. To achieve this equilibrium, enriched aquafeed with natural immunostimulants is essential to success. In this trend, 6 weeks feeding trial was conducted to evaluate the effects of Ceratonia siliqua syrup (CSS) and Zingiber officinale powder (ZOP) in Nile tilapia (Oreochromis niloticus) reared under a zero-water exchange. The immune-antioxidant, growth, physiological responses, and the antioxidant/inflammatory pathways-associated genes as well as ammonia tolerance were evaluated. Fish (weighing 25.85 ± 1.42 g) were randomly housed into six groups (n = 30 fish/group; ten fish/replicate; three replicates/group). The control group was fed a basal diet without any additives. The second (CSS1.25) group was fed a diet supplemented with 1.25% CSS. The third (ZOP0.5) and fourth (ZOP1) groups were fed diets supplemented with 0.5 and 1% ZOP. The fifth (CSS1.25 + ZOP0.5) and sixth (CSS1.25 + ZOP1) groups were fed diets supplemented with 1.25% CSS and 0.5 or 1% ZOP. All treatments were kept without water exchange for 6 weeks. Findings revealed the most notable improvement (P < 0.05) in growth rate (final body weight and specific growth rate) and survival rate in fish fed with dietary ZOP and CSS1.25 + ZOP0.5 diets. Hepato-renal markers (alanine and aspartate aminotransferases, urea, glucose, and cortisol) and lipid peroxides (malonaldehyde) were declined by CSS and/or ZOP diets. Immuno-antioxidants (immunoglobulin M, lysozyme, superoxide dismutase (SOD), and reduced glutathione) were significantly boosted (P < 0.05) in the ZOP1 and CSS1.25 + ZOP0.5 groups. In addition, CSS and/or ZOP diets markedly (P < 0.05) upregulated antioxidant-linked genes (SOD and glutathione peroxidase) and downregulated the stress gene (heat shock protein 70) and pro-inflammatory cytokines (interleukin-1β and tumor necrosis factor-alpha). In addition, CSS and/or ZOP diets decreased fish mortality during ammonia stress. The ZOP1 diet was significantly reported of having the best outcomes (P < 0.05) throughout the measured indices. Overall, our findings demonstrate that dietary ZOP and CSS at the optimum doses can improve growth, immune response, and physiological functions of O. niloticus reared in stressful conditions (unchanged water) for the sustainable aquaculture industry.