Res u Its
The 96-h LC50 of Gramoxone and detergent to O. niloticus were 0.08m111 a.nd 0.004g/1,
respectively (Fig la & lb). Mortality was 85% an.d 100% with 4.51-n1 and 4.8inl. of Gramoxone
while 50% and 75% mortality were recorded with 0.2g and 0.25 g of detergent, respectively. No
mortality was recorded at 0.1g of detergent to the fish. The fish species showed differences in
tolerance to the same concentration of toxicant. Mortality at 4.5ml of Grarnoxone at 96-h was
80% and 90% while the mortality at 0.25g of detergent at 96-h was 70% and 80%. The fingerlings
showed initial disturbed swimming behaviours such as erratic movement, rapid opercula movement
and gasping at th.e surface. This was followed by blackening of the whole body, unusual lethargy
ancl tendency of the fish to settle at the bottom, motionless with slow opercular movement.