The present study aims to assess the pollutant impact from everyday untreated or partially treated industrial wastes, wastewater treatment plants and Baghdad Medical City wastewater discharge into Tigris River, Baghdad, Iraq. Water samples were collected from seven locations of the Tigris River near Baghdad Medical City in November 2018. Morphological characteristics and biochemical methods were used to characterize Escherichia coli and Klebsiella isolates revealing that the Tigris River accumulate different amounts of antibiotic-resistant E. coli and Klebsiella sp. isolates and that pattern of resistance is different in each site. E. coli was the predominant bacterial contaminant at site 1 which is near sewage of several hospitals in Baghdad Medical City. The influence of different water quality parameters (total dissolved solids, electric conductivity, alkalinity, turbidity, total hardness, calcium, magnesium, sodium, potassium, phosphate ion, nitrate, sulphate, chloride) and heavy metals (Cd, Zn, Co, Cu, and Ni) were investigated at bacterial contaminated site 1. Besides, physiological parameters (pH value and temperature) were applied. The results revealed that these parameters were within Iraqi standards levels with a slight increase in pH and temperature at site 1.

Heavy metal poisoning means an excess of the required concentration that is found naturally on earth. In the present experiment, it has been observed that the natural water source surrounded by mountains is also polluted with arsenic because these heavy metals like arsenic are naturally contained in rocks that accumulate in the water source with soil erosion and rain. In this experiment arsenic was found in the water of Chhilpura pond, in which the haematology and biochemistry of catfish (Clarias batrachus) were studied, it was found that the RBC, haemoglobin, PCV, MCV, MCH, platelets, glucose and protein contents of catfish were found to be relatively low as compared to the control, whereas the WBC was observed to be higher to control and differential leucocyte count fluctuations were observed. It can be inferred from this experiment that heavy metals such as arsenic alter the haematology and biochemistry of catfish (Clarias batrachus).