While sexual phenotypes are typically thought of as permanent, many marine fishes change sex during adulthood, a strategy called sequential hermaphroditism. Multiple factors, including changes in gene expression patterns and associated endocrine/molecular processes, contribute to altering behavior and morphology required for sex change. Social status is often a key driver behind the “decision” to change sex. We investigated whether social interactions trigger sex change from hermaphrodite to male in mangrove rivulus fish. Hermaphrodites reproduce mainly via self-fertilization, meaning that switching to male could be costly for future reproduction because only hermaphrodites have reproductive assurance. However, changing sex to male could be a survival tactic in difficult conditions, especially given the high cost of maintaining ovaries. In this study, we placed pairs of hermaphrodites together for eight weeks, allowing dominant-subordinate relationships to form and took videos to quantify aggressive and submissive behaviors. We examined external appearance and gonadal histology to quantify features indicative of sex change. Using qPCR, we examined patterns of expression for genes responsible for the development of female-typical or male-typical traits in the brain, liver, and gonad. We predicted that subordinate fish would show an increased propensity to change sex due to the energetic costs of engaging in antagonistic interactions with dominant individuals. We expect to see greater development of testicular tissue and regression of ovarian tissue in subordinates, along with upregulation of male-biased and downregulation of female-biased genes. This study will increase our knowledge of how social interactions affect physiological processes that dictate sexual phenotype.