<p>Oxygen availability is a critical environmental factor influencing the physiology and behaviour of aquatic organisms. This study investigated the effects of chronic exposure to varying oxygen levels for 56 days on the respiratory and locomotor behaviours of African catfish (<i>Clarias gariepinus</i>) juveniles (mean body mass: 92.0 ± 6.6 g). Three groups of fish (<i>n</i> = 8 per treatment) were acclimated for 56 days to normoxic (6 mgL⁻¹), moderately hypoxic (3 mgL⁻¹), and extremely hypoxic conditions (&lt; 1 mgL⁻¹). During acclimation, the fish were fed three times daily at 3% of their body weight with a commercial feed. Following acclimation, air-breathing frequency, gill ventilation rates, and general swimming activity were assessed. Results showed that reduced oxygen levels elicited slight changes in air-breathing frequencies which were not statistically significant across treatments. The mean air-breathing frequencies ranged from a highest of 1.11 ± 0.24 breaths min⁻¹ in the normoxia group, followed by 0.90 ± 0.21 and 0.91 ± 0.18 breaths min⁻¹ in the moderate hypoxia and extreme hypoxia groups respectively. Gill ventilation also remained unaffected. Swimming behaviours of <i>C. gariepinus</i> were largely affected when exposed to extreme hypoxic conditions. These findings suggest that <i>C. gariepinus</i> juveniles exhibit a degree of behavioural resilience to chronic hypoxia, with limited adjustments in respiratory behaviour. The decline in locomotor activity under extreme hypoxia may reflect an adaptive response of the fish to conserve energy in an oxygen fluctuating environment which is relevant for aquaculture systems and natural habitats increasingly affected by deoxygenation.</p>