Worldwide, freshwater ecosystems are becoming increasingly turbid due to human activities. It is within these ecosystems that the largest number of exotic fish invasions, and native fish extinctions, occur. To date, there is no universal mechanism to explain why this pattern exists. Fishes are predominantly visual species and evidence shows that visual feeding is severely compromised when high turbidity levels are present. In contrast, my research will show that a high proportion of fishes that invade turbid habitats possess non-visual sensory specialisations, and thus have the capability to feed under turbid conditions. The ultimate aim of this project is to show that the sensory biology of fish can largely explain freshwater fish invasions and native declines on a global scale.