and 27.9–42 mm(mean= 31.5; sd= 2.97) in reservoir (n=30), maximum shell diameter 18.6–24.1 mm (mean=21; sd=1.60) in river (n=20)and 18.4–27.2 (mean=21; sd=1.68) mm in reservoir (n=30),minimum shell diameter 13.13–15.22 (mean=14.46;sd=0.65) in river (n=20) and 13.24–17.36 (mean=14.58;sd=1.27) in reservoir.