Metabolomic insights into fish osmoregulation: Unveiling adaptive mechanisms to salinity change

Salinity fluctuation is a major environmental driver influencing fish physiology and aquaculture performance. Metabolomics offers a systems perspective on the small molecule networks underlying osmoregulation. This review synthesizes studies across fish species to identify conserved metabolic responses to salinity change, including shifts in energy metabolism, amino acid turnover, and organic osmolyte synthesis. We evaluate the strengths and limitations of current analytical platforms (NMR, LC-MS, GC-MS) in metabolite coverage and identification, and highlight emerging approaches such as spatial metabolomics, multi-omics integration, and machine learning. By linking metabolic patterns to physiological and aquacultural outcomes, this work clarifies the molecular basis of salinity adaptation and offers actionable guidance for improving salinity tolerance in aquaculture.