The Dalhousie Hardyhead is found in Dalhousie Springs on the edge of the Simpson Desert in northern South Australia (SA).
The Dalhousie Hardyhead is a small elongate fish that grows to 80 mm. They are usually brown in colour with a series of darker spots running along their body, one above the mid-lateral line, the rest below it. They are difficult to distinguish relative to other Craterocephalus species. Hardyhead can be distinguished from most other fish by their elongate shape, pointed head and slightly iridescent mid-lateral band.
Ecology/Way of Life:
The Dalhousie Hardyhead inhabits about seven springs. These are typically larger springs with large warm pools and outflows. The Dalhousie Hardyhead can usually be found actively foraging around the margins during the day. Little is known of their ecology. Dalhousie Hardyhead eat algae and small invertebrates such as snails and insects. It is not known whether breeding occurs seasonally or year round. Based on aquarium observations they scatter adhesive eggs on aquatic plants. Offspring probably mature within six months. Dalhousie Hardyhead can be found in the wild in temperatures up to 41.8°C. This is the highest voluntary tolerance of any Australian freshwater fish, and one of the highest in the world.
Interaction with Humans/Threats:
This species is not commonly kept in aquariums mostly due to the difficulty in obtaining them. They make good pets though and can be bred in captivity. Their habitat was incorporated into Witjira National Park in 1985. Previously it was part of Mount Dare cattle station. They are formally listed as restricted due to their limited range. The main long-term threat is lowering of groundwater pressure. Additional threats could come from the introduction of exotic fishes into the springs such as Gambusia holbrooki (Damnbusia), which could prey upon and compete with Dalhousie Hardyhead. Nearby flowing bores have been capped which should help to prevent groundwater pressure lowering.
Craterocephalus dalhousiensis was described by Ivantsoff and Glover in 1974. The genus name is based on Greek, cratero meaning strong or sturdy, cephalus meaning head, and the species is named dalhousiensis after the location where they are found.
Unmack, P. J. (2003). Australian Desert Fishes. http://www.utexas.edu/tmm/sponsored_sites/dfc/australia/
Wager, R. & Unmack, P. J. (2000). Fishes of the Lake Eyre Catchment of Central Australia. Queenslan Department of Primary Industries, Brisbane. p. 90.
Zeidler, W. & Ponder, W. F. (1989). Natural History of Dalhousie Springs. South Australian Museum, Adelaide. p. 125.
Text: Peter J. Unmack & Rob Wager. Distribution map: Peter J. Unmack. Photographer: Ross Felix.
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