Mercury is a persistent metal that can cause serious effects on the environment. The aim of this study is to relate erythrocyte nuclear abnormalities [ENA], the frequency of immature erythrocytes (IE) and biological variables with the concentrations of total mercury (THg) in fishes on the Buenaventura Bay. The collected are lisa (Mugil cephalus), Croaker (Stellifer fuerthii), mojarra (Diapterus aureolus), and nato (Cathorops multiradiatus). M. cephalus and C. multiradiatus were negative correlations between ENA ‰ and blood THg concentrations (0.76, 0.91). For S. fuerthii and C. multiradiatus showed negative correlations (0.77, 0.67) between EI ‰ with THg levels in blood. The biological variables were related to THg levels in muscle, C. multiradiatus obtained strong correlations (0.67, 0.69) for total weight and total length. All species bioaccumulate activating of THg, confirmed the presence of this pollutant in the environment.