Contents of moisture, protein and lipid were analyzed in the muscle of mud eel fingerling ( weight: 9. 2- 15. 5g) , juvenile mud eel ( weight : 62. 3- 76. 0g) , small adult mud eel ( weight: 108. 3- 121. 4g) and big adult mud eel ( weight: 222. 8- 242. 8g) , and so was the composition of fatty acids, amino acids. The contents of protein ranged from 18. 79% to 19. 93% . The contents of lipid were fairly low. The fatty acids contained 19. 15% highunsaturated fatty acids( HUFA) . The essential amino acids accounted for 40. 98% of total amino acids. The content of glutamic acid was considerably high, reaching about 16. 95% of total amino acids.