Effect of copper on blood coagulation of Oreochromis mossambicus (Cichlidae)

The effect of copper on the blood coagulation in freshwater fish, Oreochromis mossambicus was investigated. These fish were exposed to sublethal copper concentrations over short-term (96 hr) and long-term (4 wk) periods, at 29 +/- 1 degree C (summer) and 19 +/- 1 degree C (winter), in experimental flow-through systems. Copper concentrations applied during short-term exposures were 0.16 mg/l and 0.40 mg/l, respectively, while 0.40 mg/l copper was applied during the long-term exposures. After a photocymographic observation of blood, during all the phases of coagulation was made, it was evident that there were delays in the blood coagulation times, as well as decreases in the shear modulus (elasticity) of the clots formed, after the exposure of the fish to copper concentrations at both temperatures. Copper was found to induce haemophilia at 29 +/- 1 degree C and 19 +/- 1 degree C, while at the latter it also induced thrombocytopenia. Thus exposure to copper lead to coagulation defects, which caused haemorrhage in the body tissue, which can eventually cause the death of those fish.