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.
A. A. Dada
The cost of acquiring a fingerling for stocking had always been haphazardly fixed to the detriment of the fish farmer because the cost of acquisition has no economic consideration of its cost of production. More often that not the fish farmer pays more far above the cost of production. This paper looks into the economics of producing one fingerling in two separate outdoor culture systems aerated and unaerated.