The studied fish tend to accumulate Pb, Mn and to some
extent Cd in gills. Gills are the main route of metal ion exchange
from water [26] as they have very large surface areas
that facilitate rapid diffusion of toxic metals [25]. Therefore, it
is suggested that metals accumulated in gills are mainly
concentrated from water. This is in agreement with the findings of Moore and Ramamoorthy [24]. They reported the
lack of correlation between Pb residues and feeding habits in
aquatic organisms. Similar results for high Pb concentrations
in gills were recorded by Kargin [34], Avenant-Oldewage and
Marx [35], Abu Hilal and Ismail [37] and Qadir and Malik [26].
Also, Eisler [30] reported that fish's hard tissues had consistently
higher accumulations of Mn than soft tissues.