Extreme temperatures and altered freshwater flow regimes associated with climate change are predicted to cause large-scale fish mortalities in Northern Australia by increasing the frequency and severity of hypoxic episodes. Here, we used the iconic barramundi (Lates calcarifer) as a model species to examine resting oxygen consumption rates (ṀO₂) and tolerance to acute hypoxia in five different sub-populations spanning 12° of latitude. Fish were obtained from commercial hatcheries at Gladstone, Townsville, Broome, Karumba and Darwin. Fish were maintained at two temperatures (26°C or 36°C), representing the seasonal thermal range across Australia for this species. Resting ṀO₂ was lower at 26°C (mean = 1.46 ± 0.26 mg O₂ kg^-1 min^-1) than at 36°C (mean = 3.10 ± 0.43 mg O₂ kg^-1 min^-1). All populations exhibited a common and clear trend in response to decreasing oxygen tension, with fish maintaining a constant ṀO₂ between 100% and 30% saturation, below which ṀO₂ exhibited a steep decline. Mean critical oxygen tension ([O₂]_crit) across all populations was lower at 26°C (15.44 ± 3.20% saturation) than at 36°C (21.07 ± 3.92% saturation). Overall, we found that both hypoxia tolerance and aerobic resting metabolism are conserved across the distribution of barramundi in Australia.