SOME HEMATOLOGICAL AND BIOCHEMICAL CHANGES IN TILAPIA, Oreochromis niloticus And Tilapia zillii EXPOSED TO MIXTURE OF COPPER AND LEAD.

A hematological and biochemical study was coducted on thefreshwater fish Oreochromis niloticus and Tilapia zillii. The fish wereacclimated to laboratory conditions for two weeks before use. Then the fishwere exposed for 12 weeks to a mixture of copper and lead at a ratio 1:1 ofthe LC50 of both metals. Hematological and biochemical analyses werecarried out every two weeks during the exposure period. Results indicted thefollowing:In the hematological study, there was a significant increase in the totalerythrocytes count (RBCs), as well as the hematocrite (Ht) and meancorpuscular hemoglobin concentration (MCHC) in O. niloticus uponexposure to the heavy metals mixture .This increase was observed after 10weeks for RBCs count, from the 6th week of exposure till the end of theexperiment 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 and12; the increase in Ht occurred at weeks 10 and 12; while a decrease inMCHC was noticed during the entire period of exposure. On the other hand,hemoglobin content (Hb) decreased significantly starting from the secondweek of exposure till the end of the experiment for O. niloticus. Similardecrease 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 glucoseconcentration for O.niloticus, while serum glucose was significantlyincreased in metals treated T. zillii. For both species, non significant changeswere noticed in Liver and muscle's glycogen levels. However, serum proteinlevels were significantly increased in O. niloticus, but changes were nonsignificant in T. zillii. On the other hand, muscle total protein showed asignificant decrease after 10 weeks of exposure in O. niloticus. Suchsignificant decrease in muscle total protein of T. zillii appeared only duringthe 12th week of exposure. Changes in serum creatinine and uric acid levelsin O. niloticus starting from the 8th week of exposure till the end of theexperiment.