Allometry, condition index and sex ratio in freshwater mussel Lamellidens corrianus (Lea, 1834) were studied from the freshwater lake at Rajshahi, Northwest Bangladesh during the summer 2013. The collected mussel specimens ranged from 3.69 cm to 9.98 cm in length, and 4.82 g to 80.67 g in weight. The study was focused on the relationships between length-height and length-weights (length-total weight, length-tissue wet weight, length-shell wet weight, length-tissue dry weight and length-shell dry weight), which were found not to be significantly different between male and female (P<0.05). The calculated regression equation of length-height relationship for the entire study period was H= 0.5215L-0.1482 for combined sex. The equations of length-total weight, length-tissue wet weight, length-shell weight, length-tissue dry weight and length-shell dry weight relationships of mussel were W= 0.1756L2.6775, W= 0.0261L2.8919, W= 0.0261L2.5524, W= 0.0065L2.8946 and W= 0.095L2.5109, respectively for combined sex. The relationships between length and height were linear, while that between length-weights follow the non-linear pattern. The overall male to female sex ratio was 1: 0.92 and did not differ significantly from the expected 1: 1 ratio (x2-test, P<0.05). The condition index for male, female and combined sex was 13.54, 13.97 and 13.74, respectively. The results of this study will provide baseline information for fisheries researchers and for the further assessment and management of mussels in the freshwater ecosystems of Bangladesh.
