This innovation relates to the Prebiotic potentials of Marine macro-seaweeds, especially brown macro-algae Sargassum polycystum. It can be used as prebiotic food, feed additive or feed supplement especially for the young (e.g.fish fry and fingerlings) of farmed aquatic species. Tests show that the oral intake of Sargassum polycystum (containing the indigestible polyssacharides, fucoidan) as dietary supplement for Marine fish species enhances growth performance and feed efficiency