Abstract: In this study, we used standard methods to analyze and compare the nutritional components in the muscles and skins of Anguilla japonica cultured in the seawater and freshwater, including the proximate composition, amino acids, fatty acids and minerals. The results showed that in both seawater- and freshwater-cultured Anguilla japonica, the levels of moisture, crude proteins and ash in the skins were significantly lower than that in the muscles, but the fat level was significantly higher (P0.05). Compared to those cultured in the seawater, the freshwater-cultured Anguilla japonica had significantly higher level of crude proteins in the muscle (P0.05). The contents of total amino acids in the muscles of the seawater- and freshwater-cultured Anguilla japonica were 50.22% and 54.10% respectively, and it were 42.56% and 45.80% in the skins respectively. The content of delicious amino acids was significantly higher in the skins than that in the muscles of fish cultured in both environments (P0.05). The content of unsaturated fatty acid (UFA) ranged between 65.96% and 67.51% in the muscles and skins of Anguilla japonica cultured in the seawater and freshwater, and C18:1n9 was the main component (38.64%44.79%). The contents of Fe, Ca, Cu and Na in the muscle of the seawater-cultured Anguilla japonica were significantly higher than those in the freshwater-cultured fish (P0.05). The contents of Fe, Mn and Na in the skin of the seawater-cultured Anguilla japonica were also significantly higher (P0.05). In the contrast, the level of Zn was significantly lower in Anguilla japonica cultured in the seawater (P0.05). In conclusion, the nutritional value of Anguilla japonica cultured in the freshwater could be slightly higher than that of the seawater-cultured fish, especially in terms of amino acids and fatty acids, but the seawater-cultured Anguilla japonica had higher level of minerals in the muscle and skin.