The present investigation was carried out to evaluate the residual behavior of
sublethal concentralions of two herbicides. cinmethylin (0.74 and 1.47 ppm) and
anilofos (0.98 and 1.96 ppm) on the Nile fish Oroochromis niloticus for 28 days and
left for 28 days after withdrawal both herbicides as depuration period. Uptake and
accumulation of the tested herbicides are of major concem for monitoring their
residues in tissues of treated fish and water as well. Determination of cinmethylin and
anilotos residues in fish tissues was mainly done as it is important point for human
consumption. Cinmethylin and anilotos residues in water were gradually decreased
throughout the experimental course. The percentage losses of cinmethylin residues at
the end of depuration period reached 94.8% and 98.4% at 0.74 and 1.47 ppm.
respectively. The residues level was undetected in fillet (meat) during the exposure
period except at 28 days of treatment. A complete recovery of the fillet residues was
obtained in fish at the depuration period for the two tested concentrations. While in
brain. these residues were detected 3 days after treatment followed by gradually
decrease until it reached 1.78 and 3.98 ppm at the two concentrations at the end of
depuration period, respectively. Anilotos showed distinguish fast degradation in water
compared with cinmethylin. Anitofos had residues of 0.96 and 1.93 ppm one hour after
treatment using 0.98 and 1.96 ppm, respectively. After 28 days, anilofos residues
reached 0.06 and 0.046 ppm for the same concentration, respectively. No detectable
r~sidues of anilofos were found in water during the depuration period. In fish brain and
fillet, anilofos residues gradually increased through O-time to 7 days for the two tested
concentrations. respectively. Then, the residues decreased during the remaining
period. Anilofos accumulation' in fish showed that the amounts uptaked by fish were
greater than 100% in both brain and fillet for both concentrations. These values
obviously declined and reached 80.63% and 16.43% loss in fillet and 15.52% and
69.61% loss in brain 28 days after treatment when 0.98 and 1.96 ppm of anilofos were
used. Anilofos residues showed the same trend ot cinmelhylin in fish fillet and brain
during the depuration period.