Assessment of heavy metals and microbial loads in Nile tilapia (Oreochromis niloticus) from different farms and rivers.

Metal contamination in water bodies globally poses risks to ecosystems and human health. In Pakistan, water sources are impacted by toxic metals and microbial pollutants, affecting Nile Tilapia, a widely consumed fish in Punjab. This study assessed heavy metal and microbiological contamination in Nile tilapia from the Ravi and Chenab Rivers and nearby farms (Head Muhammad Wala, Shorkot, and Rangpur). Heavy metals, including arsenic, chromium, cadmium, mercury and lead, were analyzed using Atomic Absorption Spectroscopy, Arsenic ranged lowest from 0.15 mg/kg (scales) to highest 1.38 mg/kg (Liver), while Chromium was found to be lowest 73 mg/kg in (scales) and highest 321.83 mg/kg (Liver) in Riverine Fish, whereas in farms fish As ranged lowest from 0.05 mg/kg (flesh) to highest 0.92 mg/kg (gills),while Chromium was found to be lowest 92 mg/kg in (skin) and highest 166.67 mg/kg (Liver). Riverine fish showed elevated heavy metal levels as compared to farmed fish. Moreover, Ravi River fish also showed the highest microbial loads, including total plate counts of 15,335 cfu/g, Salmonella at 373.11 cfu/25 g, and E. coli at 76.55 cfu/g, while Chenab River fish had a significantly higher coliform count (p < 0.05). These findings suggest that farmed fish are less contaminated due to reduced exposure to industrial effluents, emphasizing the need for further research on other commonly consumed fish species in high-industrial regions.