The probiotics are very important for aquaculture because of their role in enhancing the fish health status, improving disease resistance, growth performance, and body composition, reducing malformations, improving gut morphology and the overall microbial balance. The objective of the presently reported study was to investigate effects of kefir as a probiotic product on the digestive and hepatic enzyme activities, as well as glucose level of Coruh trout, Salmo coruhensis Turan, Kottelat et Engin, 2010. The experiment was performed with four treatments: control group (no kefir), D1, D2, and D3 (kefir-supplemented diet: 10, 20, and 40 g . kg(-1) fish body mass, respectively). The activity of: alanine aminotransferase (ALT), aspartate aminotranferase (AST), lactate dehydrogenase (LDH), lipase, amylase-as well as the glucose levels were determined after 4 months. The results indicated that glucose levels (P < 0.05) and digestive enzymes (lipase and amylase) in the blood serum decreased in fish fed diets containing kefir (P > 0.05). On the contrary, the activity of liver enzymes (ALT, AST, and LDH) increased insignificantly (P > 0.05). In conclusion, digestive and liver enzyme activities were affected by quantitative changes in dietary kefir insignificantly but further research is needed to establish whether the liver and digestive enzyme physiology of Coruh trout can be affected by kefir-supplemented diets in a long-term trial.