Biology, distribution, and conservation of the Gamilaroi crayfish Euastacus gamilaroi Morgan, 1997 (Decapoda: Astacidea: Parastacidae), a freshwater crayfish from New South Wales, Australia.

This article focuses on the ecology, distribution, biology, and conservation status of *Euastacus gamilaroi* Morgan 1997, commonly known as the Gamilaroi crayfish, an endangered freshwater crayfish species endemic to high-altitude streams in New South Wales, Australia. Extensive field surveys from 2006 to 2023 expanded its known range across headwater streams in the Peel and Manning River basins, revealing habitat preferences for cool, permanently flowing streams above 960 meters elevation and highlighting its vulnerability to climate change, habitat alteration, invasive species such as *Cherax destructor*, and severe bushfires. The species exhibits slow growth, low fecundity, and specific reproductive timing linked to water temperature, with populations threatened by rising temperatures and habitat fragmentation. Conservation recommendations include habitat protection within forestry management, monitoring, public education, enforcement against illegal fishing, and consideration of ex-situ breeding programs to mitigate extinction risks.