this study was carried out to determine the effects of immunogen as a prebiotic on growth-related parameters and gut micro-flora in r. kutum fry. a basal diet was formulated using common feed ingredients supplemented with immunogen at 0, 1, 1.5, and 2 g kg-1 leading to four experimental diets. fish were randomly distributed in 500 l fiberglass tanks (1×1×0.5 m). the experiment lasted for eight ...