The Dalhousie hardyhead (Craterocephalus dalhousiensis) is a species of silverside in the family Atherinidae. It is endemic to the warm waters of Dalhousie Springs in the Lake Eyre basin, Australia, along with the similar Craterocephalus gloveri.[1] It inhabits shady areas in tropical freshwater streams at 20-39 °C, but has been recorded at 41.8 °C. Its food consists of gastropods, aquatic plants, green filamentous algae, detritus and small invertebrates; food is mainly taken from the substrate.
The species is generally golden brown with a darker brown back. A dark midlateral band runs from the snout to the base of the caudal fin. Two to three rows of pigmented scales form discontinuous lines below the midlateral band.[2] It is the only species in the genus Craterocephalus known to be sexually dimorphic.[1] Adult males are smaller and exhibit a rounded belly compared to the flattened belly of females. Males also lack the forehead concavity exhibited by females.