This study provides knowledge on reproductive traits of Trypauchen vagina, a target fish for catching, based on data analysis of 701 individuals collected in the Mekong Delta from January to December 2015. The species is a multiple spawner depositing eggs in early wet season (June–August) since gonadosomatic index reaches a high point during this period, supported by the appearance of ripe and spent gonads at that time. Male and female fish matures firstly at 16.59 and 16.81 cm in total length respectively. The species displays high batch fecundity (4,000–12,750 eggs/female). Knowledge of length at first maturity and spawning season is essential for local authorities to set the suitable fish length and time for fishing. The results provide fundamental information on the reproductive biology and contributed to knowledge for fish population sustainable management.