Length-weight relationships are presented for 30 fish species captured from April 2002 to January 2004 in Lake Niushan, China. The values of the exponent b in the lengthweight relationships (W=aLb) ranged from 2.845 to 3.435 and the median of b was 3.103,whereas 50% of the values ranged between 3.032 and 3.203. In the eight examined species,sexual dimorphism did not affect the length-weight relationships, except in the cases of Siniperca chuatsi and Cultrichthys erythropterus. The application of the length-weight relationships presented here should be limited to the observed length ranges.