Abstract
Elucidating the metabolic basis of sexual dimorphism is critical for the effective management of sequential hermaphrodites in aquaculture. The four-finger threadfin (Eleutheronema tetradactylum) is a commercially significant protandrous species; however, the metabolic landscapes characterizing its sexual maturity remain unexplored. In this study, we established a foundational metabolomic baseline by profiling brain and gonad tissues from sexually mature males and females using UHPLC-Q-TOF-MS. Multivariate statistical analysis revealed distinct tissue-specific dimorphism, with gonadal tissues exhibiting significantly greater sex-specific metabolic divergence than neural tissues. We identified sex-specific alterations in key metabolic networks, including aminoacyl-tRNA biosynthesis, nucleotide metabolism (purine/pyrimidine), and the glutamine-glutamate axis, which collectively support the high biosynthetic demands of ovarian development. Notably, the brain exhibited subtle yet specific shifts in neuro-lipid signaling, including arachidonic acid metabolism and tryptophan pathways, suggesting a neuroendocrine regulatory role rather than global metabolic remodeling. To our knowledge, this is the first tissue-resolved metabolomic dataset for a protandrous hermaphrodite fish. This study establishes a preliminary metabolomic baseline of biochemical differentiation in E. tetradactylum, identifying candidate biomarkers for sex identification and providing a foundation for future investigation into the metabolic regulation of protandrous hermaphroditism.