The study was conducted to evaluate the effect of dietary administration of fructooligosaccharides (FOS) on hematological parameters, growth rate, glucose, cortisol concentration, digestive enzyme activities and total bacteria in the intestine in stripped catfish fingerlings. FOS was included at 0, 0.5%, 1.0%, 1.5%, and 2.0% in fish diet. After 90 days of FOS administration, the density of red blood cells (RBC), white blood cells (WBC), hematocrit, hemoglobin in the treatments 0.5% and 1.0% were significant higher (P6cell/mm³), (112; 129x10³ cell/mm³), (51.8, 52.3%), ( 21.8, 27.5g/100 mL). The growth of fish increased significantly when supplied 0.5% and 1.0% of FOS in the diets such as final weights (57.9 and 59.2 g), daily weight gain (0.487 and 0.502 g/day), specific growth rate (1.576 and 1.600%/day), respectively. The survival rate were the highest of observed in the 0.5% and 1.0% FOS group (100%) and the lowest in 1,5% FOS (82,1%). Similarly, digestive enzyme activities such as amylase (stomach and intestine), pepsine, trypsine, chymotrypsine significant enhance at the level 0.5% and 1.0% FOS. Total bacterias in the intestine were 7.2 and 7.3 log(cfu/g) in treatments 0.5% and 1.0% FOS. They were significant higher than other treatments (P

At the end of experiment, glucose and cortisol concentrations in 0.5% and 1% were significant lower than other treatments when the fish were stress by high density. The plasma concentration of glucose and cortisol of the fish were 93.4 - 91.1 (mg/100mL) and 47.2 - 45.4 (ng/mL), respectively. Based on the results, the optimal level of FOS should be 0.5% and 1.0% to improve growth rate, stress defense of stripped catfish fingerlings.