3.7. Histological study
The detoxification of toxic substances takes place in liver and the histopathological results indicated that liver tissue was severely affected by As(III). In the control and treated group, no histopathologic lesions were observed when compared to the fishes exposed to As(III) which showed dystrophy in the form of hepatic necrosis. The histological changes in liver tissues of control, test and treated fishes are shown in Fig. 6. During the present investigation, intense degenerative changes in the liver of test group fishes were observed marked with irregular shaped hepatocytes, prominent cytoplasmic vacuolization and condensation of the nuclei (Fig. 6b). The most conspicuous changes with karyohexis and karyolysis were also observed in As(III) exposed fishes. Similar toxicity effects were noticed in freshwater fish, tilapia [21] and gibel carp Carassius auratus gibelio [46] when exposed to arsenic. The present study also revealed that the hepatocytes and other cells of the liver in control and bacteria treated groups were normal and systematically arranged with a centrally placed nucleus (Fig. 6a and c) indicating the effectiveness of Exiguobacterium in removing As(III) from water thereby reducing arsenic toxicity in fishes.