However, the Hb content and Ht were observed to decrease in juvenile beluga that were fed an inulin-incorporated diet at 2 g kg−1 and 3 g kg−1 (Reza et al., 2009). In our study, the RBC in fish fed the two inulin-supplemented diets and the two JA-supplemented diets increased significantly compared with that of fish in the control group. In contrast, RBC modulation was not observed in hybrid surubim that were fed an inulin-incorporated diet (5.0 g kg−1 ) for 15 days or in beluga fed an inulin-supplemented diet (10.0–20.0gkg−1) for 8 weeks (Mourino et al., 2012; Reza et al., 2009).