Nocturnal weakly electric fish generate electric organ discharges (EODs) to image their surroundings and communicate in darkness. Some species, known as pulse fish, generate EODs at 20-120 Hz with long irregular intervals while species known as wave fish produce EODs at regular uniform intervals with frequencies as high as 2000 Hz. Modulations of EOD rate and waveform convey or reveal important information to conspecifics during social interactions. Changes in EOD rate are controlled centrally through regulation of the pacemaker or command nuclei that coordinate action potentials in the electric organ cells (electrocytes) to produce the EOD. We focus here on changes in EOD amplitude and duration that are ultimately regulated by hormones that target electrocyte action potential characteristics. These changes occur over timescales ranging from minutes to days in response to prevailing organismal, environmental, and social conditions. Multiple hormones, including melanocortin peptides, leptin, and steroid hormones, exert direct and sometimes interactive effects on the electrical properties of electrocytes to produce corresponding changes in EOD waveform. Comparisons between pulse and wave fish reveal both common endocrine mechanisms of EOD waveform regulation as well as important differences that are potentially a function of differences in life history.