Integrating hematological profile and biomarker analysis for metals and metalloids ecotoxicological assessment on Wallago catfish and Indian carp health in Head Siphon, Mailsi, Pakistan.

Bioaccumulation of metals and metalloids in marine environments poses a significant risk to both human and aquatic health, with seasonal fluctuations substantially influencing its dynamics and magnitude. This study investigated the impact of metals and metalloids exposure on the health of Wallago attu (Wallago catfish) and Catla catla (Indian carp) inhabiting the Head Siphon, Mailsi, Pakistan. This study involved the seasonal (May 2022, October 2022, April 2023) assessment of physicochemical properties and the concentrations of several metals and metalloids-copper (Cu), chromium (Cr), arsenic (As), cadmium (Cd), nickel (Ni), zinc (Zn), and iron (Fe)-in water samples. Additionally, we evaluated hematological indices and antioxidant enzyme such as superoxide dismutase (SOD), catalase (CAT), and peroxidase (POD) in both fish species. Our analysis revealed seasonal variations in water quality and metal/metalloid concentrations. The results indicate summer exhibited the highest metal concentrations, following the trend: Cu > Zn > Fe > Cd > Cr > As > Ni. Specifically, Cu peaked in summer, Cr and Ni remained relatively stable, Cd decreased from summer to winter/spring, and Zn mirrored Cu trends, while Fe significantly reduced in winter. Several trace elements and water parameters (pH, nitrate) exceeded USEPA permissible limits, indicating water quality deterioration and potential ecological risks. Antioxidant enzyme profiling revealed species-specific oxidative stress responses. In W. attu, SOD varied distinctly across organs and seasons, with unique winter CAT trends suggesting complex antioxidant defense mechanisms. C. catla displayed elevated SOD, POD, and CAT levels, indicative of a robust stress response. Species-specific hematological variations, potentially indicative of metal/metalloid contamination, were observed. Notably, increased white blood cell counts in spring suggested pollutant-induced immune responses. This study reveals a complex interplay between environmental stressors and fish health, showing that exposure to metals and metalloids can cause adverse physiological effects in W. attu and C. catla. These findings are important because they suggest a potential risk to human health through the consumption of contaminated fish.