| Summary: | The effects of three feed additives in a low fish meal diet on growth, antioxidant capacity and intestinal microbiota of <i>Penaeus monodon</i> were studied to enhance the understanding of these effects and to provide basic data and a reference for the formulation and optimization of feed for <i>P. monodon.</i> A total of 630 healthy, homogenous shrimp (4.58 ± 0.05 g) were randomly divided into seven groups with three replicates per group and 30 shrimp per replicate in a breeding barrel (500 L). The additive names and amounts were 0 (CT); vitamin B<sub>6</sub>, 100 mg/kg (V1); vitamin B<sub>6</sub>, 200 mg/kg (V2); phytase, 1000 U/kg (P1); phytase, 2000 U/kg (P2); 0.2% yucca extract (Y1); and 0.4% yucca extract (Y2). The experiment lasted 8 weeks. The results showed that compared to CT, V1 and Y1 had a significant increasing tendency toward weight gain (WG) (<i>p</i> < 0.05) and had a significant decreasing tendency in the food conversion ratio (FCR) (<i>p</i> < 0.05). P2 had a significant increasing tendency in α-amylase activity (<i>p</i> < 0.05), and P1 had a significant increasing tendency in total superoxide dismutase (T-SOD) (<i>p</i> < 0.05). The next-generation sequencing of intestinal microbiota showed that Proteobacteria was the most abundant phylum in the seven groups, accounting for 29.33%, 56.67%, 55%, 45.33%, 73%, 39.33% and 64.33% of the total. Compared to CT, the Proteobacteria was significantly high (<i>p</i> < 0.05) in P2 and Y2, and the Bacteroidota in all other groups decreased significantly (<i>p</i> < 0.05). The functional prediction of FAPROTAX indicated that there was no significant difference (<i>p</i> > 0.05) in functional components among all groups. According to growth performance, antioxidant capacity and effects on intestinal microbiota, vitamin B6 (100 mg/kg), phytase (2000 U/kg) and yucca extract (0.2%) can be recommended as additives for the diet of <i>P. monodon</i>.
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