Behavioral, molecular, and hormonal mechanisms work together to impact sensory processes, communication, and mate choice. This study investigates the evolution of communication and sexual dimorphism through an analysis of intrasexual variation in behavioral and molecular mechanisms in Apteronotus leptorhynchus, or the brown ghost knifefish. Although knifefish behavior is well described, gene expression studies in the brain are fairly novel, and few studies have looked at the correlation between behavior and gene expression in the brain within individuals. The brown ghost knifefish has unique, sexually dimorphic communicative behaviors which involve electric signals and can be systematically quantified by measuring electric organ discharge frequency (EODf) and chirp rates (rapid frequency modulations). In this study, we investigated the hypothesis that intrasexual variation in behavioral and molecular traits will be higher in males than in females due to sexual selection pressures, and that this variation is the result of changes in hormone receptor expression. To this end, we show that behavior is dimorphic in brown ghost knifefish, both in terms of EODf and chirp rates. Males have higher baseline frequencies and chirp rates than females. In addition, there is significantly more intrasexual variation in chirp rates within males. To determine if this sexually dimorphic behavior is due to changes in hormone receptor expression, we looked molecularly at expression of the androgen receptor, and of the estrogen receptors ESR1 and ESR2A. Preliminarily, our data suggest that perhaps receptor gene expression levels are not dimorphic in the brain, and therefore a different molecular mechanism seems to be driving this dimorphic behavior. Upon further investigation, we found that hormones, and specifically 11-ketotestosterone, seem to be likely candidates. This work supports the hypothesis that behavioral variation is greater in male knifefish, but the presence or absence of molecular dimorphism in the brain specifically could not be confirmed.