For aquaculture management, the presence of unwanted predatory or trash fishes in the newly stocked fish ponds create a great nuisance because of their competition with desired fishes for food and shelter. In this perspective for eradication of such predatory fishes by using phytopiscicides the present study was conducted to determine the median lethal concentration (LC 50) value of Antigonon leptopus aqueous fresh leaf extract on Rupchand fish (Stramoteus sinensis) in laboratory condition. Piscicidal effect had been studied by using five different concentration of aqueous leaf extract (40mg/L, 80mg/L, 120mg/L, 160mg/L and 200mg/L) on fingerlings of Rupchand fish. The phytopiscicidal effect was tested for 24 hours of exposure and the LC50 value 57.54mg/L was estimated by probit analysis. LC50 values were found to be inversely proportional to exposure duration. Moreover, the acute (LC 100) effect that killed all the test fishes within 24-hrs was determined to be the highest concentration of 235.59mg/L. where as in control no such effect had been found. The phytochemicals present in tested plant material and also the water parameters (TDS, DO, pH etc.). The dose response mortality and behavioural changes were studied against the aquous leaf extract of Antigonon leptopus Hook. The result indicated the potential piscicidal property of this botanical. Being a potent biodegradable, easily available, eco-friendly, icthyotoxicant against environmentally hazardous synthetic chemicals, aqueous fresh crude leaf extract of this plant species may be used for eradicating unwanted predatory or trash fishes for pre stocking management of pond-based aquaculture which would be helpful for making future ecofriendly industrial product.