the objective of this study was to evaluate the antimicrobial activity of the essential oils from five brazilian piper species (piper aduncum, piper callosum, piper hispidinervum, piper hispidum and piper marginatum) against strains of aeromonas hydrophila, isolated from tambaqui (colossoma macropomum), as well as their chemical composition. the oils were characterized by gas chromatography and mass spectrometry (gc/ms), and the major compounds identified were: dillapiole (80.7 %) for p. aduncum; safrole (67.0 %), methyl-eugenol (7.2 %) and -pinene (6.6 %) for p. callosum; safrole (89.3 %) for p. hispidinervum; -terpinene (27.3 %), p-cymene (14.0 %) and -terpinene (12.0 %) for p. hispidum; -3-carene (13.1 %), propiopiperone (8.0 %) and (e)-caryophyllene (6.8 %) for p. marginatum. the brazilian piper species evaluated in this study were able to inhibit the growth of the ten strains of a. hydrophila, with minimum inhibitory concentration (mic) values ranging from 234.37 to 30,000 g ml-1. the antimicrobial activity of piper essential oils was considered strong for p. callosum, p. hispidinervum, p. hispidum and p. marginatum, with the exception of p. aduncum that presented weak activity for all strains. this is the first record of antimicrobial activity of piper essential oils against strains of a. hydrophila isolated from tambaqui, suggesting the potential for use in the treatment of infections caused by this bacterium.