Carbosulfan is a carbamate insecticide which has been widely used in agriculture. However, studies showed that carbosulfan could be highly toxic to aquatic organisms. The metabolism of carbosulfan in adult zebrafish is still largely unexplored, and the metabolites in individual or in combination may pose potential threat to zebrafish. In the present study, the bioaccumulation and metabolism of carbosulfan in zebrafish (Danio rerio) were assessed, and the main metabolites including carbofuran and carbofuran-3-hydroxy were determined. The toxicity of carbosulfan and the metabolites in individual or combination to zebrafish was also investigated. The bioaccumulation and metabolism experiment indicated that carbosulfan was not highly accumulated in zebrafish with bioaccumulation factor of 18 after exposed to carbosulfan for 15 days, and the metabolism was fast with half-life of 1.63 d. The two main metabolites were relatively persistent with half-lives of 3.33 d and 5.68 d for carbofuran and 3-hydroxy carbofuran, respectively. The acute toxicity assay showed carbofuran and 3-hydroxy carbofuran had 96-h LC50 values of 0.15 mg/L and 0.36 mg/L, which were more toxic than carbosulfan (96-h LC50 0.53 mg/L). Combination in binary or ternary mixtures of carbosulfan and the metabolites displayed coincident synergistic effects in acute toxicity with additive index (AI) values of 1.9-14.3. In the livers and gills of zebrafish exposed to carbosulfan, carbofuran and 3-hydroxy carbofuran, activities of catalase, superoxide dismutase and glutathione-S-transferase were significantly changed in most cases, and the content of malondialdehyde was greatly increased, indicating that carbosulfan and its metabolites induced varying degrees of oxidative stress. The metabolites were more persistent and toxic to zebrafish, and exhibit coincident synergistic effects in combination. These results can provide evidence for the potential risk of pesticides, and highlight the importance of a systematic assessment for the combination of the precursor and metabolites.