This study aimed to evaluate the synergistic effects of Quillaja saponaria (QS) and Yucca schidigera (YS) on water quality, growth performance and health of Nile tilapia. Fish (n=120, 11.97±0.497 g) were randomly distributed into four experimental groups in triplicates. (1) Control group (CG), fish received basal diet; (2) Yucca schidigera group (YS); fish received basal diet and 0.11 mL/m3 per week YS extract in water; (3) Quillaja saponaria group (QS), fish received basal diet supplemented with 300 mg kg-1 QS extract; (4) Mixed group (QS/YS), fish received basal diet supplemented with 300 mg kg-1 QS and 0.11 mL/m3 per week YS extract in water.
Results revealed an improvement of water quality parameters in QS/YS, YS, and QS compared to CG (P≤0.05). Fish received QS and/or YS showed higher growth performance and lower feed conversion ratio than CG (P≤0.05), with the best findings being reported in QS/YS. Using QS and/or YS improved gill health, increased intestinal villi length, and goblet cell number compared to CG (P≤ 0.05). Lymphocytes, total protein, globulin, and lysozyme activity were increased, while cholesterol, triglycerides, glucose, and creatinine were decreased in fish received QS and/or YS compared to CG (P≤0.05), with the best results being observed in QS/YS. QS and/or YS supplementation increased lipase, amylase, superoxide dismutase, catalase while reduced malonaldehyde activity compared to CG, with the highest activity being recorded in QS/YS.
Conclusively, Nile tilapia received QS and YS prompted synergistic effects that improved water quality, growth performance, immune-oxidative status, digestive enzymes, gills and intestine histomorphology.