The present study was conducted to assess the water quality and bioaccumulation of heavy metals (Cd, Cu, Pb, and Zn) in tissues of the tilapia fish (Oreochromis niloticus) and shrimp (Metapenaeus affinis), which were caught from Shatt al-Arab river near Al- Najibiya power plant in Basrah, Iraq during Mar 2018 – Feb 2019. Aquatic samples consisted of raw water from the river, drainage channel water, and demi water from the inside electric power plant. 10 parameters including the electrical conductivity, total dissolved solids, total suspended solids, the concentration of hydrogen ions, calcium, magnesium, chloride, sulphate, phosphate, and temperature were examined. The results designated that a deterioration in the water quality of Shatt al-Arab was observed during the hot months, especially in the summer season of 2018. The conductivity rates were higher than the permissible limits compared to demi industrial water. Occurrence of heavy element concentrations of Cd, and Pb were in slightly higher average level in water samples collected from river raw water (0.62 and 0.14 mg/l)  and drainage chanal water (0.17 and 0.15 mg/l)  respectively. The concentration average of the heavy metals in the investigated parts (muscle, gill, and liver) of the studied fish could be found with significant variation among examined tissues. The current study concluded that the metal concentrations in muscles of the tilapia fish and the edible parts from studied shrimps were within the limits permitted for human consumption.