Susceptibility of fish to Chattonella marina is determined by its tolerance to hypoxia

► Fish kill mechanisms by C. marina. ► A significant elevation of blood osmolality is the universal response in moribund fish exposed to C. marina. ► Both respiratory impairment and osmotic distress are important mechanisms leading to fish kill by C. marina. ► The susceptibility of marine fish both interspecies and intraspecies to C. marina inversely related to their tolerance to hypoxia.