Table 2.

Overall mean ± Standard Error (SE), range and Kruskal–Wallis One-Way Analysis of Variance test of toxic metals (Cd, Hg and Pb) measured for eleven fish species from Aiba Reservoir, Iwo, Nigeria.

Fish species	Cd (ppm) Mean ± SE	Hg (ppm) Mean ± SE	Pb (ppm) Mean ± SE
Marcusenius senegalensis	0.007 ± 0.001	0.005 ± 0.001	0.005 ± 0.001
Labeo senegalensis	0.020 ± 0.001	0.008 ± 0.004	0.020 ± 0.008
Hepsetus odoe	0.007 ± 0.001	0.005 ± 0.001	0.007 ± 0.001
Chrysichthys auratus	0.006 ± 0.001	0.004 ± 0.001	0.005 ± 0.001
Chrysichthys nigrodigitatus	0.004 ± 0.001	0.002 ± 0.000	0.005 ± 0.001
Clarias ebriensis	0.013 ± 0.005	0.008 ± 0.003	0.009 ± 0.003
Clarias macromystax	0.008 ± 0.003	0.006 ± 0.003	0.008 ± 0.003
Channa obscura	0.012 ± 0.004	0.008 ± 0.003	0.014 ± 0.006
Tilapia zillii	0.013 ± 0.006	0.007 ± 0.004	0.024 ± 0.011
Sarotherodon galilaeus	0.009 ± 0.003	0.004 ± 0.002	0.021 ± 0.009
Oreochromis niloticus	0.022 ± 0.008	0.011 ± 0.005	0.021 ± 0.008
Total
Mean ± SE (ppm)	0.012 ± 0.002	0.006 ± 0.001	0.010 ± 0.001
Range (ppm)	0.001–0.125	0.000–0.067	0.001–0.100
Species number (S)	11	11	11
Sample number (n)	168	168	168
(df = 10)	6.25	12.59	7.67
P-value	0.794	0.247	0.794