Proximate composition, microbial quality and heavy metal concentration of fresh Nile tilapia fillet in Lake Tana, Ethiopia

Nowadays, consumption of fish is becoming a public health concern due to quality and safety issues. This study was designed to assess the proximate composition, microbial quality, and heavy metal accumulation in the Nile tilapia fillet at three selected landing sites in Lake Tana. Fifteen samples were collected and analyzed. The mean moisture, ash, fat, protein, salt, and water activity were 81.76%, 0.98%, 1.88%, 14.04%, 0.14%, and 0.9869, respectively. The proximate contents varied slightly among sites but were not significantly different (p > 0.05). The mean aerobic mesophilic bacteria, <i>Staphylococcus aureus</i>, total coliform, and fecal coliform counts were 6.30 log CFU/g, 2.91 log CFU/g, 1.51 log MPN/g, and 0.89 log MPN/g, respectively. Such high microbial loads and the high counts of fecal coliforms are indicative of poor handling practices and unsanitary processing that might lead to foodborne illnesses and economic losses. In addition, the mean concentration of heavy metals in the tissue samples decreased in the order of chromium (0.165 mg/kg) > arsenic (0.085 mg/kg) > lead (0.054 mg/kg) > cadmium (0.010 mg/kg). Except for chromium, the concentrations of the assessed metals were below the maximum permissible limits. Long-term chromium exposure, especially in its hexavalent form, can pose significant health risks like respiratory issues, gastrointestinal distress, and even cancer. Therefore, identifying contamination sources, employing proper waste management strategies, continuous monitoring of heavy metal levels, and proper fish handling practices are highly recommended to address the health implications of microbial contamination and elevated chromium concentrations.