Koi fish (Cyprinus carpio) is one of the fish species of high economic value. The world-wide importance of common carp (Cyprinus carpio) in inland fisheries stems from its role in contributing to animal protein supply for human demand. This study evaluated the effects of probiotics on growth performance of juvenile koi carp (Cyprinus carpio). A 30 day feeding experiment was conducted to measure the effects of adding a commercial preparation of Lactobacillus acidophilus (LA; 6 × 109 CFU/ kg DM) in the diet of koi carp. The experimental diet contained 6 × 109 CFU LA/kg of a control diet. The incorporation of LA as a dietary probiotic in the basal diet for koi carp showed no significant effects on growth performance and Koi carp survival rate.