Studies on the effects of dietary inclusions of plants in gredientson feed physical characteristics are particularly important becausethe non-starch polysaccharide fractions of plant ingredients have the potential to reduce expansion and affect the hardness of feeds(Ainsworth et al., 2007). Hardness and water stability are impor-tant factors which determine nutrient retention capacity as well asthe sinking velocity of pellets (Baeverfjord et al., 2006; Chevananet al., 2009; Kraugerud et al., 2011). The hardness of pellets gener-ally affects their preference and acceptability by fish, where softerpellets are usually preferred to harder pellets