Acute toxicity of mesocarp of Azadirachta indica (L.) (Neem plant) on fingerlings of Heterobranchus bidorsalis

Abstract

The piscicidal potential of water-extract mesocarp of Azardirachta indica  was investigated in static biossay experiment with continuous aeration to determine its acute toxicity.  The 96-hLC₅₀ was 97.42mg/l while the threshold value was 31.12mg/l.  The extract led to an initial increase in opercula ventilation rates which then decreased significantly.  The computed regression equation (y) = 4.624 + 6.352 Logc. (r=0.72) and the fish exhibited respiratory distress, loss of balance and erratic swimming prior to mortality.  The usefulness of A. indica as piscicidal plant is discussed.