Some Physicochemical Parameters and Heavy Metals Concentration in Water and Organs of Oreochromis niloticus (Linnaeus, 1758) in Ajiwa Reservoir, Katsina State

Ajiwa Reservoir serves as a vital drinking water source and protein source to the nearby communities and Katsina metropolitan. Fishes are a great dependable source of protein and assessment to determine their safety or otherwise is very crucial. In this work, four vital organs (gills, gonads, liver and muscles) collected from Ajiwa reservoir in Katsina state were analyzed for some heavy metals (Cobalt, Copper, Manganese, Nickel, and Lead). This preliminary investigation was carried out between September to December (2023) to expose additional information on the concentration of heavy metals in both water and tissues of Oreochromis niloticus, four sampling stations were randomly chosen for the survey along the bank of the reservoir. Samples were collected fortnightly throughout the research. The mean physicochemical parameters of the Ajiwa reservoir were pH (7.10±0.48), Temperature (22.93±4.02), Transparency (12.61±2.46), Conductivity (113.97±10.63), DO (6.78±1.09), and BOD (3.52±0.88). Atomic Absorption Spectrometry (AAS) instrument was used to determine the heavy metal concentrations in the samples and their levels compared with the World Health Organization (WHO, 2020) specified maximum levels. The results showed the concentration of heavy metals in the water to be (mg/L) Co (0.45±0.23), Cu (0.05±0.03), Mn (0.06±0.09), Ni (0.10±0.07), and Pb (0.40±0.18). Co, Mn, Ni and Pb were higher than the set standards limits of WHO (2023). The results indicate that the concentration of heavy metals in the analyzed fish tissues are in (mg/L) Co (1.03±0.16), Cu (0.13±0.05), Mn (0.10±0.19), Ni (0.18±0.22) and Pb (0.21±0.66). The concentration of Co, Ni and Pb were above the set standards of WHO (2020). Co, Mn and Pb concentrations mostly in the liver and gills were higher than the maximum permissible limit recommended by standard bodies.