To detect the bacterial function, the intestinal microbiota of adult zebrafish was collected from each experimental group (CON vs. HF, WT vs. cpt1b–/–, WT vs. pparab–/–) and transplanted to larval germ-free zebrafish to identify whether intestinal microbiota reshaped by different diet components or genetic background could cause lipid accumulation in germ-free zebrafish. The gene discussed is CPT1B; the disease is hydrops fetalis.