In this study, physiological responses of brook trout (Salmo trutta fario) were researched after the different stunning methods with biochemical enzymes. Icy water, electroshock, CO2, hypoxia, and head hitting were tried as stunning techniques to 75 fish and the alterations in the blood biochemistry parameters were analyzed. Alkaline phosphates (ALP), and amylase (AMS) were found as not statistically important, but alanine transaminases (ALT), aspartate transaminases (AST), creatin chitinase (CK), CK-MB (one of the CK isoenzymes), gamma glutamil transferase (GGT) and lactate dehydrogenase (LDH) levels were important (p<0.05). According to these results, the different stunning techniques affected the stress levels and physiological situations of brook trout. The study findings showed that killing techniques resulting in a shorter period were more suitable for animal welfare.