Fish has great socioeconomic, cultural, and nutritional importance for Amazonian populations. Despite
all health benefits, fish can accumulate great amounts of mercury (Hg). The entry of Hg in aquatic trophic
chains is an issue of concern to animal and human health. Higher risks of human exposure are strongly
related to fish consumption. Upper Solimoes population has one of the highest fish consumption rates of
the Amazon. This study aimed to access the concentration of total Hg (THg) in muscle, liver, and gills of
17 species of fishes marketed in the Upper Solimoes Region and Health Risk Assessment. Higher concentrations were observed in Carnivores/Piscivores. The highest THg concentration was found in liver of
Cichla ocellaris (4.549 mg/g) and the lowest in gills of Hoplosternum littorale (0.002 mg/g). Most species had
higher THg concentrations in muscle>liver>gills, in the Ebb period, and liver>muscle>gills, in the Flood
period. Hoplias malabaricus, Pseudoplatystoma fasciatum, Plagioscion squamosissimus, Ageneiosus inermis,
and C. ocellaris presented average THg concentrations above the safe limit stablished by WHO. THg levels
in C. ocellaris, H. malabaricus, P. squamosissimus, P. fasciatum, and Semaprochilodus insignis were higher
than those found in fish of heavily impacted areas. Signs of bioaccumulation and biomagnifications of Hg
can already be observed in this region. The Western Amazon Region urgently needs government actions
to inhibit Hg release in aquatic ecosystems and to advise this population on the safe amount of fish to be
eaten according to species and period of the year.
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