Regarding serum lysozyme content in tilapia, assays showed no difference (P[0.05) among the treatment groups. Furthermore, probiotics treatments remarkably increased respiratory burst activity compared with control, with T-2 showing higher values than T-1 and T-3. This indicated that treatment with probiotics, B. coagulans B16 and R. palustris G06, as water additives could be used to enhance immune and health
status, thereby improving growth performance of O. niloticus.