A hematological and biochemical study was coducted on the
freshwater fish Oreochromis niloticus and Tilapia zillii. The fish were
acclimated to laboratory conditions for two weeks before use. Then the fish
were exposed for 12 weeks to a mixture of copper and lead at a ratio 1:1 of
the LC50 of both metals. Hematological and biochemical analyses were
carried out every two weeks during the exposure period. Results indicted the
following:
In the hematological study, there was a significant increase in the total
erythrocytes count (RBCs), as well as the hematocrite (Ht) and mean
corpuscular hemoglobin concentration (MCHC) in O. niloticus upon
exposure to the heavy metals mixture .This increase was observed after 10
weeks for RBCs count, from the 6th week of exposure till the end of the
experiment for Ht and throughout the whole time of exposure for MCHC.
For T. zillii, the increase in the RBCs count was noticed at weeks 4,6 and
12; the increase in Ht occurred at weeks 10 and 12; while a decrease in
MCHC was noticed during the entire period of exposure. On the other hand,
hemoglobin content (Hb) decreased significantly starting from the second
week of exposure till the end of the experiment for O. niloticus. Similar
decrease was noticed for T. zillii (except the value at 8 weeks of exposure)
and continued till the end of the exposure period.
Non significant changes were observed in the serum glucose
concentration for O.niloticus, while serum glucose was significantly
increased in metals treated T. zillii. For both species, non significant changes
were noticed in Liver and muscle's glycogen levels. However, serum protein
levels were significantly increased in O. niloticus, but changes were non
significant in T. zillii. On the other hand, muscle total protein showed a
significant decrease after 10 weeks of exposure in O. niloticus. Such
significant decrease in muscle total protein of T. zillii appeared only during
the 12th week of exposure. Changes in serum creatinine and uric acid levels
in O. niloticus starting from the 8th week of exposure till the end of the
experiment.