Metabolomic Profiling identifies Biomarkers of Sexual Dimorphism in the Brain and Gonads of Matured Eleutheronema tetradactylum.

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.