Wildfire prevalence has increased drastically around the world, exacerbated by climate change, resulting in devastation to ecosystems and the organisms therewithin. Australian bushfires are of particular concern given Australia’s extensive biodiversity and numerous endemic species. While terrestrial impacts are often the primary concern for fires, the aquatic environment is also at risk. Ash from fires can directly descend into aquatic environments or be introduced as runoff, and which can release heavy metals and contaminants such as polyaromatic hydrocarbons. The physiological effects of bushfire ash on aquatic animals are not well understood, nor is their subsequent coping and recovery ability. Two native Australian freshwater species, the long-armed shrimp (Macrobrachium australiense) and the blue yabby (Cherax destructor), were selected to examine their physiological responses following exposure to Australian bushfire ash. We found that the shrimp were significantly more sensitive to ash than the crayfish. Metabolic oxygen consumption was measured, and the enzymatic activity of cytochrome c oxidase and lactate dehydrogenase were assessed in three tissue types (gills, hepatopancreas and muscle). Thus, insight is gained into the species method of cellular respiration. The sensitivity and effects of ash exposure are important to adequately evaluate the effects of bushfires. The ability for animals to contend with ash exposure will allow for identification of critical areas where monitoring and conservation efforts should be made following bushfires.