ABSTRACT Biological response modifiers such as pro and prebiotics have been recently used in aquaculture showing abilities as immunostimulants, enhancing resistance to different fungal, bacterial and parasitic pathogens and tolerance to environmental stress. This experiment evaluated three different concentrations (0.05, 0.1 and 0.5%) of &#946;-1,3/1,6 glucans on nonspecific immune parameters of channel catfish Ictalurus punctatus. Results showed that intake supplementation with 0.05% of &#946;-1,3/1,6 glucans provides a greater immunostimulation over the fourth treatment week. Significant higher differences (P < 0.05) were obtained on parameters related to phagocytic activity on blood cells, also other assays showed more reactive cells to nitroblue tetrazolium (NbT) stain on spleen and head kidney analysis. We conclude that the use of 0.05% of &#946;-1,3/1,6 glucans added to a commercial diet improves nonspecific immune system of channel catfish I. punctatus.