Dietary dandelion extract improved growth performance, immunity, intestinal morphology and microbiota composition of golden pompano Trachinotus ovatus

•Dietary 1.00 g/kg dandelion extract (DE) supplementation significantly increased weight gain rate of golden pompano.•Dietary DE improved intestinal morphology of golden pompano.•Dietary DE improved intestinal microbiota of golden pompano. The gut microbiota plays an important role in growth performance, intestinal mucosal barrier, digestion and absorption of nutrients and immune responses. In this study, we investigated the effect of dietary dandelion extract (DE) on growth performance, expression of immune related genes in the spleen, intestinal morphology and microbiota of golden pompano (Trachinotus ovatus). Golden pompanos were fed three diets adding 0 (DE0), 0.50 (DE1), 1.00 (DE2) g/kg DE for 8 weeks. At the end of this trial, dietary 1.00 g/kg DE supplementation significantly increased weight gain rate and feed intake compared to those of the control group (P < 0.05). Meanwhile, dietary 1.00 g/kg DE supplementation significantly up-regulated transcription levels of glutathione peroxidase and interleukin 10 in the spleen of fish. However, dietary DE supplementation had no significant effect on transforming growth factor β1, glutathione reductase and catalase in the spleen of fish. Moreover, dietary 0.50–1.00 g/kg DE supplementation improved the richness and diversity of gut microbiota, increase the relative abundance of Actinobacteria and Firmicutes, and reduce the proportion of harmful microbial taxa. Furthermore, dietary DE improved intestinal morphology and immunity by increasing intestinal goblet cells numbers and decreasing epithelial lymphocyte numbers. In conclusion, dietary 1.00 g/kg DE supplementation was clearly beneficial for golden pompano by improving growth performance, gut morphology and microbiota and it could use as a functional feed additive in aquaculture.