Tarebia granifera is an ovoviviparous and parthenogenetic freshwater snail indigenous to South East Asia. T. granifera was introduced into many areas of the world as a result of human activity and caused detrimental effects on native freshwater snails. T. granifera also served as the first intermediate hosts of many digenetic trematodes. Specimens of T. granifera were collected seasonally in Jinlun River, S.E. Taiwan, from April, 2003 to January, 2004. The embryo composition in the brood pouches was compared among seasons. We found the species was fertile and the embryo composition was similar throughout the year. The maximum embryo number occurred in October, 2003, and the minimum occurred in January, 2004. T. granifera was reared to compare juvenile releasing rates in summer and winter. More juveniles were released per mother-snail in summer than in winter. And low water temperature seemed to inhibit juvenile release in cold days. The survival rates of brooded juveniles outside brood pouches were tested. Except the smallest size group (shell height=0.25~0.50mm), all others (0.5~1.25mm) had high survival rates approaching 100%. About 15% of the snails were infested by unidentified xiphidiocercariae. Larger snails were more likely to be infected and the infected snails were less likely to be fertile than uninfected ones.