“…In addition, in species with sexually dimorphic EODs, female and juvenile electric fish waveforms can be masculinized by introducing exogenous androgens via injection or implantation (Bass, 1986;Bass and Hopkins, 1983;Franchina, 1997;Hagedorn and Carr, 1985;Hopkins et al, 1990;Meyer et al, 1987;Meyer et al, 1984). Earlier studies investigating the effects of steroid hormones on EOD waveform have focused on electrophysiology of electrocytes, changes in EOD waveform, measured after days (Few and Zakon, 2001) or weeks (Hagedorn and Carr, 1985;Meyer, 1983;Mills and Zakon, 1991 Brachyhypopomus pinnicaudatus display circadian rhythms with greater magnitudes and they respond more dynamically to stressors and social manipulations than females do (Franchina et al, 2001;Franchina and Stoddard, 1998;Markham and Stoddard, 2005;Stoddard et al, 2006a).…”