Asian seabass is a bony fish from the Latidae family with a wide geographic distribution in the tropical Indo-West Pacific region. It is a migratory fish that is born in brackish water, spends most of its life in freshwater and returns to the sea to breed. Its ability to tolerate changes in salinity makes it a good candidate for studying the salinity adaptation response in teleosts. We compared the transcriptome of two major osmoregulatory organs i.e. gills and kidneys of young juvenile Asian seabass reared in freshwater and seawater. The euryhaline nature of Asian seabass was found</p><p>to be highly pliable and the moldability of the trait was further confirmed by histological analyses of gills and kidneys. The differentially expressed genes included genes related to osmoregulation, tissue/organ morphogenesis and cell volume regulation as central to the osmo-adaptive response. Additionally, genes coding for mucins were up-regulated specifically under saline conditions whereas several genes important for growth and development as well as circadian entrainment were specifically enriched in the freshwater conditions. Routing of the circadian rhythm mediated by salinity changes could be the initial step in salinity adaptation and possibly migration in euryhaline fish species such as the Asian seabass.