The 2013 Minamata Convention seeks to reduce anthropogenic emissions of mercury (Hg) and enhance public awareness of Hg exposure and impacts. The treaty also requires countries to increase monitoring of Hg in the environment in order to reduce human exposure and examine the efficacy of the treaty over time. Campos dos Goytacazes, Brazil, is located in a watershed with a history of significant Hg deposition from gold mining and sugarcane farming. This study provides previously unpublished data on the presence of Hg in certain fish in Campos and the awareness of mercury contamination among the local population. We analyzed Hg concentrations in five commonly consumed fish species by the residents of Campos and found concentrations to be elevated in some species, to vary significantly among species, and to correlate with trophic levels likely due to biomagnification. A sample survey of people in Campos found that education levels negatively correlated with knowledge of the presence of Hg in fish and the negative health effects of both Hg and heavy metal contamination in general. These findings have potential importance for understanding Hg levels in the environment, underscore the necessity for public awareness and education efforts regarding Hg contamination (as called for in the new Convention), and provide baseline measures for the presence of Hg in fish in Campos and public awareness related to this presence. These data can be compared to future studies to examine the efficacy of the Convention and other efforts to reduce Hg emissions and exposure to Hg in this part of Brazil.