variations observed in different studies may be explicable by a
number of factors, including differences in activities of methyl
malathion biotransforming enzymes [39], genetic differences between
species strains, or a prior history of inducer exposure, the
presence of impurities in the Folidol 600 or simply interlaboratory
variations in experimental protocols.
The current results suggest that the 6-h exposure to low concentrations
of Folidol 600 (0.5–1.0 mg L1) promoted hematological
responses in O. niloticus similar to those observed in other fish
exposed to organophosphorus pesticides as: Carbofuran and
Molinate [40] and Folidol 600 [6,38,39].
Heath et al. [40] and Areechon and Plumb [41] suggest that this
response probably occurs due to a possible lesion on gill tissue,
resulting in an internal hipoxya and a stimulation of erythropoiesis.
However, the fish groups exposed to the higher concentrations
of pesticide didn’t show significant increases in HTC, which indicates
the loss of ability to maintain homeostasis, probably due to
exhaustion or injury of hematopoietic tissue