Post-fire, changes in water quality due to ash and post-fire sediment run-off into waterbodies can compromise the physiological functioning of freshwater animals, with significant effects on short and long-term health and survival. This project will examine how Australian freshwater fish, frogs and invertebrates are affected by acute and chronic exposure to such post-fire water quality changes as elevated temperature, low oxygen levels and run-off exposure to ash and sediment loads. The research is needed in the aftermath of the 2019–20 wildfires as the threshold tolerances of freshwater aquatic animals for ash and post-fire sediment loads in Australian waterways are unknown. Having this information would inform the management of waterway flows to redirect run-off away from waterways, sufficiently dilute sediment slugs and ensure that they move through sensitive habitats quickly enough before they can adversely affect animal health, and to undertake preventative population relocations to protect animals until waterways recover.