The purpose of this research is to determine the concentration levels of
heavy metals, Le., Cd, Pb, Hg, Cu, Zn and Mn In (OI8ochromis ni/oticus) of rats fed on
these fish at'different locations of Maryout-Iake. The biological evaluation of rats red
On these fish was also carried out. The obteined results indicated thai, Maryoul lake-
fish and its water contained higher heavy metals especially, Cd, Pb and Hg than the
river Nile-fish and its waler samples. There are no significant differences of heavy melals concenlration In both
rels serum and liver, which fed on conlrol and Nile 1ish, whereas rels fed on Maryoul
lake-~sh shOwed significant Increase. Biological evaluation indicated \hat no
significant differences were found in bolh liver and kidney functions of rats, fed on
diets contained Nile fish or casein meanwhile, urea and cereatinine were increased in
rats fed on Maryout-fish fQr 60 days. Both lola I proteIn and lipids in serum did not affect in all groups of rats,
neither fot differenl sources of 1ish nor experimental period, but cholesterol was
Increased. A signifICant decrease In haemoglobin perameler of rats at Ihe end 01
feeding period of Maryout lake-fish had been achJeved. Growth rale, feed
ecnsurreucn and feed efficiency ratio didn't affect, except for rats fed on diel
conlalnlng Maryoul-fish tor 60 days.