Caspary (1992) reported that increased intestinal villi leads to increased surface area for nutrient absorption, thereby improving growth performance and feed utilization in animals. Several researchers proposed that fermentation of inulin produces several substances that stimulate intestinal cell proliferation, which in turn results in increased villus height (Blottiere et al., 2003; Rehman et al., 2007; Nabizadeh, 2012). The present study demonstrated that dietary supplementation with inulin (5.0 g kg−1 ) and JA (5.0 g kg−1 and 10.0 g kg−1 ) resulted in greater villus height in all parts of the intestine, although a significant increase in villus height was observed only in the anterior and middle parts. However, the effect of dietary inulin on carnivorous fish appears to be different. For example, Olsen et al. (2001) reported that a high level of dietary inulin (150 g kg−1 dietary inclusion) had negative effects on the ultrastructure of the gastrointestinal tract of Arctic char (Salvelinus alpinus).