Comparison of Heavy Metal Deposition in Edible Muscles of Nile Tilapia (Oreochromis niloticus) and Crucian Carp (Carassius carassius) in Lake Ziway, Ethiopia

Abstract

Lake Ziway is a fresh Lake playing an important role in the lives of many people in the region. These may make the Lake Ziway to receive various kinds of pollutants enriched with heavy metals through different mechanism. The purpose this study was to conducted analysis of heavy metal accumulation in the edible muscles of Nile Tilapia  and curican carp fish species which are among the most common types of fish consumed by the local people and found widespread in the lake Ziway. The analysis of heavy metals including Cd, Pb, Ni, Cu, and Zn were conducted for water samples and  from edible muscles of two fish species including Nile tilapia and Curician carp. Data were subjected to statistical analysis. The result of physicochemical properties of the water samples from the study sites in the Ziway lake indicated no significance differences in temperature and pH among the three sites. However, significance differences were observed in other parameters like electrical conductivity (EC), total dissolved solids (TDS) and suspended solids (SS). Site 1 has demonstrated significantly the highest EC (1245.12±5.34 µS/cm), TDS (756.10±1.50mg/L) and SS (24.5±0.15 mg/L). The concentrations of heavy metals in water samples from Lake Ziway  at site 1 (close to floriculture industry) presented significantly the highest amount of all the tested metals including Cd (2.71mg/L), Cu (4.88mg/L), Ni (8.10mg/L), Pb (6.06mg/L) and Zn (12.12mg/L). Significantly the highest load of metal accumulations in fish muscles were observed at site 1 (near floriculture industry) in Nile tilapia with load of Zn(100.37), Cd (6.05), Ni(4.70), Pb (5.76) and Cu (47.54)mg/L. The comparison of heavy metal accumulation across lake sites  in fish muscle samples indicated that the highest accumulations were obtained for Cu and Zn; small amounts of Cd, Ni & Pb.