Reproductive biology and gonadal cycle of Indian Potasi, Neotropius atherinoides (Bloch 1794) in Bangladesh

The present study was conducted to investigate the reproductive biology of Neotropius atherinoides in Bangladesh Fisheries Research Institute, Floodplain Sub-station, Santahar, Bogura, Bangladesh. A total number of 70 fish samples were collected on monthly basis from Atrai River and Jamuna River during the period from September 2021 to August 2022. The highest mean value of the gonado-somatic index (GSI) was recorded in July (12.55±2.50), whereas the lowest was found in January (0.46±0.11). Highest individual fecundity (7000±1900) and ova diameter (0.50±0.07 mm) was also observed in July. From the histological observation of the ovary, early peri-nucleolar stage, late peri-nucleolar stage, yolk vesicle stage, yolk granule stages were identified where the highest percentage (80%) of mature oocytes were observed in July. Based on the GSI, fecundity, and gonadal histology, the breeding season of N. atherinoides was observed from May to August and recorded a remarkable peak in July. In case of length weight relationship (LWR), the coefficient of determination value (r2) was found 0.95 and slope was found b=1.02 which indicated the pattern of negative allometric growth of this species as b<3. In contrast, an increase was recorded in the fecundity associated with the rise of total length, body weight, and gonad weight, showed a significant linear relationship. This study would assist in the development of induced breeding techniques and provide valuable information for the sustainable management of this population in the inland open ecosystem.