Brackish water fish are species that thrive in environments where freshwater and saltwater mix, such as estuaries and mangroves. These fish have adapted to varying salinity levels, allowing them to survive in conditions that are too salty for most freshwater fish and too fresh for most marine species. Common examples include tilapia, mullet, and snook. These fish play a crucial role in their ecosystems, serving as both predators and prey. They contribute to the biodiversity of brackish habitats and are important for local fisheries. Understanding their biology helps in the conservation of these unique environments.