Murray Hardyhead, Craterocephalus fluviatilis McCulloch 1912
Murray Hardyhead, Craterocephalus fluviatilis. Source: Gunther Schmida. License: CC BY Attribution-Noncommercial-ShareAlike
A small, silvery-green to dark golden hardyhead with a reticulated pattern along the back formed by dark scale margins, a pale silvery to golden belly, and a distinct mid-lateral stripe.
Video of Murray Hardyhead conservation and recovery efforts in the Victorian Mallee region.
Murray Hardyhead, Craterocephalus fluviatilis McCulloch 1912
Endemic to the Murray and Murrumbidgee river systems in few isolated areas in Victoria and South Australia.
Historically, Murray Hardyhead were known to occur as far upstream as Narrandera on the Murrumbidgee River, Wentworth on the lower Darling River in New South Wales, in wetlands near Swan Hill and Mildura in Victoria, and in parts of the Murray River and its tributaries near Renmark, Swan Reach and the Lower Lakes near the Murray River mouth in South Australia. Over the past five decades, the species has dramatically declined in distribution and abundance, and scientists fear that the Murray Hardyhead is on the verge of extinction.
Remnant populations now only occur in the Lower Murray Region and Lower Lakes Region of South Australia. In Victoria, until recently, the Murray Hardyhead is found in Round Lake, Woorinen North Lake and Cardross Lakes, along with some salt lakes, irrigation channels and creeks in northern Victoria. No viable populations have been found in New South Wales for some time. The species has been recorded in freshwater wetlands in South Australia, although in Victoria, remnant populations of Murray Hardyhead occur in saline habitats.
Murray Hardyhead school in open water habitats, preferring relatively salty fringing wetlands in floodplains and lakes. Historically they survived in isolated wetlands on floodplain fringes during dry seasons, dispersing out over the floodplain during wet seasons.
Dorsal fin IV-VII + I, 5-8; Anal fin I, 6-9; Pectoral fin 11-13.
Body laterally compressed, moderately deep and elongate; greatest body depth 4.0-5.1 in SL; mouth small, protrusible, lips not thick, gape restricted by labial ligament from one third to half way along premaxilla; teeth small, in single row and restricted to anterior part of both jaws; rear edge of jaw does not reach eye; eye diameter 3.2-3.9 in HL.
Scales on body small, thin, deciduous, almost circular, with circuli obvious and complete; scales on top head large and irregularly shaped; vertical scale rows 31-35; horizontal scale rows 10-12.
Two small, separate, short-based dorsal fins; origin of 2nd dorsal fin directly above anal fin; caudal fin forked; pectoral fins positioned high on sides; pelvic fins abdominal.
|To 7cm SL|
|Silvery to golden above, paler with a silvery sheen below, a silvery dark mid-lateral stripe, and a reticulate pattern above formed by dark scale margins. The fins become bright yellow during spawning.|
|Omnivore - feeds on micro-crustaceans, aquatic insects (midge and mosquito larvae), and algae.|
|The Murray Hardyhead is primarily an annual species (i.e. most fish reach maturity, spawn and die within a year), and spawns from September to April, mostly during late spring to early summer.Females deposit batches of eggs with adhesive filaments amongst aquatic vegetation, particularly Eel Grass.|
EPBC Act: Endangered under the the Environment Protection and Biodiversity Conservation Act 1999 (EPBC Act)
IUCN Red List of Threatened Species: Endangered
NSW: Listed as Critically Endangered (Fisheries Management Act 1994 (New South Wales: August 2013 list)
VICTORIA: Listed as Threatened (Flora and Fauna Guarantee Act 1988 (Victoria: May 2014 list)
The major threats to remaining Murray Hardyhead populations are habitat degradation, the impact of non-native species such as Eastern Gambusia, European Carp, and Redfin, drought, salinity, and the regulation of rivers and creation of barriers to dispersal.
Adams et al. (2011) found the Craterocephalus fluviatilis comprised four genetically distinct populations.
Historically the species has been confused with a number of species including C. eyresii, C. amniculus and (Crowley and Ivanstoff 1990 However, only the latter species is also found in the southern tributaries of the Murray-Darling Basin (Ivanstoff and Crowley 1996).
Historically the Murray Hardyhead had been confused with a number of species, including Craterocephalus amniculus, C. eyresii, and C. fulvus. Crowley and Ivantsoff (1990) revised the genus, recognising C. fluviatilis as valid. This is the only species found in the southern tributaries of the Murray-Darling Basin (Ivanstoff and Crowley 1996). C. fluviatilis differs from C. eyresii and the Darling Hardyhead, C. amniculus, in scale counts, body depth and in having a single row of inward pointing teeth in the upper and lower jaw.
|The specific name fluviatilis is from the Latin meaning ‘of a river’.|
|Craterocephalus fluviatilis McCulloch, 1912. Proc. R. Soc. Qld. 24: 49 pl. 1(1). Type locality: North Yanko Creek, Narranderra, NSW.|
Bray, D.J. & Thompson, V.J. 2018
Murray Hardyhead, Craterocephalus fluviatilis McCulloch 1912
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