Air‐breathing in fish is believed to have arisen as an adaptation to aquatic hypoxia. Although air‐breathing has been widely studied in numerous fish species, little is known about the obligate air‐breathing African bonytongue, Heterotis niloticus . We evaluated if abiotic factors and physical activity affect air‐breathing patterns in fingerlings. The air‐breathing frequency ( f AB ) and behavioral responses of H. niloticus fi...