Toxicity of copper and zinc to tilapia (Oreochromis niloticus) singly and in mixtures

Abstract

Mixture toxicity experiments reflect environmental pollution in a more realistic manner since the environment is often contaminated with cocktails of pollutants. This study was aimed to determine the 96hr LC50 of copper and zinc as single metal and in mixture to Tilapia (Oreochromis niloticus) and the metal uptake of these two metals. The 96hr LC50 values for copper were 2.404 mgL- 1 and 2.431 mgL- 1 in replicates 1 and 2 respectively. While, the 96hr LC50 values for zinc were 13.327 mgL- 1 and 11.479 mgL- 1 in replicates 1 and 2 respectively. The mean 96hr value in mixture was 6.05 mgL-1 • Comparing the 96hr LC50 between single and metal mixture, it shows that the 96hr LC50 of the mixture was less toxic than copper singly but more toxic than zinc singly. Generally, Tilapia (Oreochromis niloticus) accumulated greater concentrations of zinc in its whole body as compared with copper in all concentrations of mixture. Further study should be done to investigate the 96hr LC50 of copper, zinc and its mixture as experiments employed in the lab is different from the natural waters.