Study the effect of hexavalent chromium on some biochemical, citotoxicological and histopathological aspects of the Orechromis spp. fish.

In nature chromium occurs in divalent, trivalent and hexavalent forms. Hexavalent chromium predominates over the trivalent form in natural waters. Knowledge of acute toxicity of a xenobiotic often can be very helpful in predicting and preventing acute damage to aquatic life in receiving waters as well as in regulating toxic waste discharges. The 96 h LC50 tests can be used to obtain toxicity data as rapidly and inexpensively as possible. In the present study, results showed a significant decrease in total glycogen, total lipids and total protein of liver, muscles and gills after 24 and 96 h of exposure to 96 h LC50 of hexavalent chromium (43.7 mg L(-1)). Cytotoxicity of metals is important because some metals are potential mutagens able to induce tumors in humans and experimental animals, the treatment of(Cr VI) at 43.7 mg L(-1) was for 24 and 96 h, respectively. DNA was extracted after treatment from brain and liver of the tested fish. Our results showed appearance of polymorphic bands at the long treatment interval (96 h) ofhexavalent chromium. However, these bands were not appeared when the fish were exposed to the (Cr VI) for the short treatment interval (24 h). Histopathological changes were seen in liver, muscle and gills sections of chromium-exposed fishes. The obtained results were discussed in the study research.