The influence of water quality on fish tissues and blood profile in Arab al-Ulayqat Lakes, Egypt

This paper aims to investigate the relationship between water quality variables and fish blood profiles in Arab al-Ulayqat Lakes in Abu Zaabal, Egypt, during the years 2021 and 2022. It also investigates how water pollution affects the quality of Nile tilapia (O. (Oreochromis) niloticus). Water quality parameters were measured, and concentrations of six metals—namely Cu²⁺, Cd²⁺, Fe²⁺, Ni²⁺, Pb²⁺, and Zn²⁺—in water and fish were determined. In addition, the hematological and biochemical parameters of fish were evaluated. Results revealed that the water in the three lakes was brackish and seriously polluted. Lake #3, in particular, was highly ammonia-concentrated and had organic contaminants and metal ions. The results showed high resistance of O. niloticus to water pollution and relatively low accumulation of pollutants in muscle tissue. O. niloticus from Lake #3 had considerable Cu²⁺ and Zn²⁺ contamination. The results of the fish examination revealed that changes in water quality variables have a significant impact on the blood profile of fish. Fish from Lake #3 showed increased levels of amino-aspartate activity transferase (AST) and alanine aminotransferase (ALT), which indicates hepatotoxicity. All fish from the lakes exhibited increased values of creatine and urea, which indicates nephrotoxicity and reduced antioxidant enzyme activity. The hazard index (HI) analysis demonstrated that heavy metals had no deleterious consequences for human health through the daily consumption of fish gathered from the Nile River, Lakes #1 and #2. However, the HI for Lake #3 showed that the investigated heavy metals adversely affected health.