Piscicidal potential of mesocarp of neem plant (Azadirachta indica L.) fruit on hybrid, "Heteroclarias"

The piscicidal potential of water-extract mesocarp of Azadirachta indica (L) was studied in static bioassay experiment with continuous aeration to determine its acute toxicity The mortality rate and opercular ventilation under laboratory conditions over 96 hr exposure were monitored. The 96 hrLC50 was 81.28 mgl(-1) while the threshold value was 21.13 mgl(-1). The fish exhibited respiratory distress (such as gasping air), loss of appetite, loss of balance and erratic swimming prior to mortality.