Propolis as a Growth Stimulant for Nile Tilapia ( <i>Oreochromis niloticus</i> ) Juveniles

Propolis, a natural resinous compound with bioactive properties, has gained attention as a potential growth stimulant in aquaculture. This study investigated the effects of dietary propolis supplementation on growth performance, molecular biomarkers, intestinal histomorphometry, and digestive enzyme activity in tilapia juveniles (Oreochromis niloticus), and saved 50% of the amount of fish meal used in feed. A total of 210 fish (15.55 ± 0.21 g) were distributed into 21 aquaria and fed six isonitrogenous (30% crude protein) and isocaloric (1820 kJ/kg) diets containing graded propolis levels (0, 2, 4, 6, 8 and 10 g/kg) for 86 days. We added two controls for the experiment, the first to assess propolis efficiency with and without its supplementation, and the second to monitor its plant-based protein substitution ability of 50% fish meal. Results indicated that 0.4% and 0.6% propolis supplementation significantly enhanced growth metrics, including final body weight, weight gain, specific growth rate, and feed conversion ratio, comparable to the control (B) diet (p < 0.05). Propolis inclusion also improved protease and amylase activities, with the highest enzymatic activity observed at 0.4% supplementation. Molecular analysis revealed upregulation of hepatic IGF-1 gene expression in the 0.6% propolis group, suggesting enhanced growth potential. Intestinal histomorphometry demonstrated increased villus height, width, and surface area in propolis-fed fish, indicating improved nutrient absorption. Furthermore, whole-body proximate analysis showed optimised protein deposition in 0.4% and 0.6% treated groups. These findings suggest that propolis at 0.4%-0.6% dietary inclusion can increase the effectiveness of plant protein mixture to replace half amount of dietary fishmeal, enhance digestive efficiency, and stimulate growth in tilapia juveniles, offering a sustainable alternative for aquaculture feed optimisation.