Bio-accumulation of Heavy Metal in Silver Catfish <I>Chrysichthys nigrodigitatus</I>, <I>Tilapia zillii</I> and <I>Macrobrachium macrobrachion</I> Caught in Badagry Creek, Lagos Nigeria

Abstract

The people of Lagos state depends on fishes and other aquatic products for their source of protein. Thus, the need to verify the safety of the fishes for consumption by the people. The sampling, handling and process were as directed by American Public Health Association (APHA).The species checklist indicated that the Bagrids, Chrysicthys nigrodigitatus; Cichlids, Tilapia zillii and fresh water prawn of genus Macrobrachium were the dominant fin and shell fish species in the Creek. Results of the analysis of trace metals in the organs of Tilapia zillii indicated that the metals were differentially accumulated in different organs of the fish. In the tissue, the orders of accumulation were gills (52.360±25.964 Fe), Gut (2.180±0.480 Zn), Gills (0.300±0.056 Mn), Bone (0.091±0.125 Pb), Bone, gills, Gut and flesh (0.010±0.00 Cr) and 0.001±0.000 Cd) is uniform for all the organs under investigation in mg/kg respectively.While the order of metals bioaccumulation in the Macrobrachium macrobrachion (most dominant freshwater prawn) the order of bioaccumulation is Cu > Zn > Mn > Fe > Cr > Pb > Cd with the value of 26.100±6.280, 21.250±1.744, 14.585±28.277, 6.067±3.608, 0.257±0.049, 0.023±0.009, 0.002±0.000 respectively with all values in Mg/Kg. However, the general trend of accumulations in all the organisms were Tilapia zillii > Chrysichthys nigrodigitatus > Macrobrachium macrobrachion. The results of analysis of variance showed that different organisms accumulate different metals in their organs differently (P<0.05). The observed level of metals in the sediments and different organisms analyzed were below the WHO standards. Therefore, there is no foreseeable adverse health problem that may arise from the consumption of the analyzed fish species.