A 45-day feeding trial using solid-state fermented orange peel (FOP) and prickly pear peel (FPP) by Brewer's yeast, Saccharomyces cerevisiae was conducted to evaluate water quality, microbiological analysis, digestive enzyme activities, gene expression, growth performance and survival of shrimp Litopenaeus vannamei as phytobiotic products feed additives. Three treatments were formulated: Control (C, only commercial diet); FOP (2.5% FOP + commercial diet) and FPP (2.5% FPP + commercial diet). 720 post-larvae shrimp (0.05± 0.09g) were divided in three experimental treatments, with three replicate tanks each and stocked with 80 PL. It was observed that weight gain, feed conversion ratio, specific growth rate and survival %  differed significantly (P<0.05) between the FPP and the control. The total vibrio population in water and shrimp intestines declined significantly (P<0.05) in FOP and FPP; whilst, the heterotrophic was significantly enhanced (P<0.05) in FOP and FPP, compared to control. All digestive enzyme activities were influenced by an increase in the hepatopancreas, stomach and intestine of shrimp fed with FOP and FPP diets. Furthermore, both growth and immune-related gene expressions increased in FPP. The present study showed that the addition of 2.5% solid-state fermented orange or prickly pear peels by Brewer's yeast, Saccharomyces cerevisiae to the shrimp diet can enhance shrimp development, intestinal bacteria, digestive enzymes and the gene expression of shrimp L. vannamei.