In the River Nile and Manzalla lake some fishers use the cyanide for catching fish. So that the present study is a contribution to the assessment of the toxicity effects of copper cyanide on the Nile Tilapia (Oreochromis. niloticus) fish. Since biochemical assessment is a useful tool for measuring environmental quality. Short term toxicity experiments were conducted to study the effect of metal cyanide complex (copper cyanide) on the metabolic enzymes viz., lactate dehydrogenase (LDH), glucose-6phosphate dehydrogenase (G6PDH), aspartate amino transferase (AST) alanineamino transferase (ALT), acid phosphatase (AcP) and alkaline phosphatase (ALP activity in (O. niloticus) fingerlings. A total of 45 fingerlings were (8±0.6 cm; 12±0.2 g) exposed to two sublethal concentrations (0.253 and 0.152 mg/L) for a period of15 days. Copper cyanide had significant (P> 0.05) effect on the metabolic enzymes, the highest activities were observed in the group exposed to 0.253 mg/L. Results suggest that metal cyanide complex significantly altered enzyme activities of fish in both the sublethal concentrations.
