Clown-knife fish (chitala ornata), an air breathing fish is one of the high values species cultured intensively in Me-Kong Delta, Viet Nam. Low dissolved oxygen concentration (DO) in water environment may affect directly or indirectly on the fish physiological responses and respiration. This study was conducted to evaluate effects of dissolved oxygen levels on the oxygen consumption from water and air of clown-knife fish at 27^oC using bimodal intermittent-closed respirometry. Fish used in experiment was from 114.12 ± 11.16 grams in normoxic treatment (8 fish) and 80.16 ± 19 grams in hypoxic treatment(7 fish) and fish had been fasted and acclimated to 27 ^oC for 2 days in controlled air conditioning room before starting measurement. The experiment consisted of two DO levels including normoxic (around 100% of saturation) and hypoxic (28% of saturation) water environment. In addition, each fish in every treatment had been measured for 2 routines, the first 20 hours-routine in normoxic water, bacteria oxygen consumption for 2 hours and finally the second 20 hours-routine in normoxic or hypoxic water, of normoxic or hypoxic treatment, respectively. In addition, standard metabolic rate of fish had been estimated after finishing every fish in normoxic treatment. The results showed that there is no significant difference in total oxygen consumption (MO₂) between the first and the second normoxic treatment of 62.44 ± 17.24 and 65.12 ± 18.09 mgO₂/kg/hr, respectively. The air consumption contributes 13.36% and 10.78% in the total MO₂. There is difference between the first and the second measurement (74.33± 16.33 and 69.52± 25.38 mgO₂/kg/hr) of the hypoxic treatment significantly (pChitala chitala in 27^oC is around 47.98 ± 11.11 mgO₂/kg/hr. In brief, Chitala ornata is able to maintain standard metabolic rate (SMR) through aquatic breathing alone in high dissolved oxygen environment but air breathing is important during lower oxygen concentrations.