Piscicidal effect of some common plants of India commonly used in freshwater bodies against target animals

Mortality caused by the aqueous extracts of leaf and stem bark of four plants belonging to family Euphorbiaceae and Apocynaceae against freshwater fish Channa punctatus has been reported. It was found that dilute aqueous solutions of leaf and stem bark were active in killing the fishes. The toxic effect of stem bark of all the plants were time as well as dose dependent. There was significant negative correlation between LC50 and exposure periods. Thus, the LC50 values of stem bark extracts of Euphorbia royleana, Jatropha gossypifolia, Nerium indicum and Thevetia peruviana were decreased from 0.050 g/l (24 h) > to 0.020 g/l (96 h); 4.61 g/l (24 h) > to 4.34 g/l (96 h); 0.097 g/l (24 h) > to 0.041 g/l (96 h) and 4.05 g/l (24 h) > to 3.17 g/l (96 h), respectively. It has been suggested that these plant products cannot be used directly in freshwater bodies, without their detailed studies on long-term effects on non-target organism as well their structure activity relationship.