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Laboratory evaluation was made to develop an environmentally safe and effective plant-origin piscicide. Piscicidal activity of different solvent extracts of Nerium indicum latex against the freshwater predatory snakehead, Channa punctatus was both time and dose-dependent, in terms of the lethal concentrations for 50% of the fish (LC50) always. Methanolic extract of N. indicum latex had LC50 of 17 mgL-1 at 24 h and 10 mgL-1 at 96 hour. Acetone, chloroform and diethyl ether extracts of N. indicum latex had LC50s of 18-23 mgL-1 at 24 h and 13-17 mgL-1 at 96 h. Exposure to sublethal doses (40% and 80% of LC50) of methanolic extract of N. indicum latex (which had maximum piscicidal activity) for 24 h or 96 h caused significant time and dose-dependent alterations in the concentrations of total protein, total free amino acid, nucleic acid, glycogen, pyruvate and lactate, and in the activity of the enzymes protease, alanine aminotransferase, aspartate aminotransferase, acid phosphates, alkaline phosphatase and acetylcholinesterase of snakehead. Thus, N. indicum latex shifts fish respiration towards the anaerobic pathway. The toxicity of the latex extract was reversible and 7 days after withdrawal, all biochemical parameters were back to normal. Thus, solvent extract of N. indicum latex can be used in aquatic environment for controlling unwanted populations of the snakehead Channa punctatus.