Dalhousie hardyhead

{{Short description|Species of fish}}

{{Speciesbox

| status = CR

| status_system = IUCN3.1

| status_ref = {{cite iucn |author=Whiterod, N. |author2=Hammer, M. |author3=Unmack, P. |author4=Mathwin, R. |author5=Gotch, T. |date=2019 |title=Craterocephalus dalhousiensis |volume=2019 |page=e.T5489A123377703 |doi=10.2305/IUCN.UK.2019-3.RLTS.T5489A123377703.en |access-date=16 November 2021}}

| taxon = Craterocephalus dalhousiensis

| authority = Ivantsoff & Glover, 1974

| synonyms =

}}

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.{{cite web | author1 = Bray, D.J. | author2 = Thompson, V.J. | name-list-style = amp | year = 2017 | title = Craterocephalus dalhousiensis | work =Fishes of Australia | access-date = 21 July 2019 | url = http://fishesofaustralia.net.au/home/species/1375 | publisher = Museums Victoria}} 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.{{FishBase|Craterocephalus|dalhousiensis|month=April|year=2019}}

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.{{cite book |last=Allen |first=Gerald |date=1989 |title=Freshwater Fishes of Australia |location=Neptune City |publisher= T.F.H. Publications|page=78 |isbn=0-86622-936-1}} It is the only species in the genus Craterocephalus known to be sexually dimorphic. 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.

{{As of|2024|07}}, it is listed as critically endangered under the EBPC Act.{{SPRAT|81512|Craterocephalus dalhousiensis}}