Metals and metalloids in frequently consumed fish species from Koka and Aba Samuel Reservoirs in central Ethiopia: seasonal accumulation, inter- organ distribution, and health risk assessment

The deposition of trace metals in freshwater had direct impacts on the ecosystem health. Consequently, in the present work, the levels of B, Zn, Cd, Hg, Cu, Ni, Fe, Mn, Cr, Se, Pb, As, and Co were determined in the organs of freshwater fish species from Lake Koka and Aba Samuel Reservoir in Ethiopia in February and July 2023. The analysis was performed using an ICP-OES after the hot plate digestion. Statistical analyses indicated that the metal levels in fish organs differed significantly (p < 0.005). The mean buildup trend of these elements in the organs of fish was liver>gill>muscle. There exists a substantial difference in the accumulation of trace metals in muscle and liver (p < 0.005). The trace metal accumulation pattern for fish types was C. carpio > C. gariepinus > O. niloticus . Seasonal variation of the trace metal concentrations in fish organs indicated elevated concentrations in the dry season. Accumulation patterns of the elements in C. gariepinus at the two sampling sites differed significantly (p < 0.005). With the exception of Pb in all fish species, the values for the possible health risk to human health from eating the examined fish species from the two sample locations were within allowable limits.