Climate change is now the foremost threat to coral reefs, following unprecedented recurrent years of mass coral bleaching on Australia's Great Barrier and many other reef locations. Climate impacts are however, occurring against a backdrop of other perennial disturbances and stresses, and these cumulative pressures are causing sustained and ongoing degradation of coral reef environments throughout the world. Also, despite the emergence of direct environmental impacts on the distribution and performance of reef fishes, habitat degradation (including coral loss and topographical collapse) represents the first and foremost threat to coral reef fishes posed by global climate change. Moreover, degradation of reef habitats reduces the capacity for fishes to mediate exposure to changing environmental conditions, making them even more vulnerable to climate impacts. There are very few species that actually benefit from climate-induced changes in environmental conditions and habitat structure and their increases in abundance does not compensate for extensive declines in abundance across a large proportion of reef fish species. Ongoing climate change and mass coral bleaching will therefore, have major deleterious impacts on the biodiversity, productivity, structure and function of reef fish assemblages, and the only way to minimise these impacts is to reduce global carbon emissions.