It was observed in this study that

It was observed in this study that O. niloticus fin.gerlings showed variations in their
tolerance of same Gratnoxone and detergent concentrations at a given period particularly as the
replicates giave different mortality. Chen and Lei (1990) reported that juveniles of shrimp, Penaeus
monoclon showed differences in tolerance to ammonia and nitrate solutions. Heit and Fingermann
(1977) noted that females of the cray fishes, Procan2barus clarki and 1-;'axonella elypeata were
much more tolerant of mercury than the males, thus the differences in tolerance of O. niloticus to
the same concentration of Gramoxone and detergent may be attributed to the male female
composition of the test fishes