Murray Hardyhead 

Murray Hardyhead Craterocephalus fluviatilis is a small silvery fish growing to about 8cm which tends to form schools and are often referred to as minnows. The Murray Hardyhead is only found in the Murray-Darling River system and is one of Australia’s most threatened species of freshwater fish.

Murray Hardyhead can be sometimes confused with the Unspecked Hardyhead which is similar in appearance and more common.

Distribution

The Murray Hardyhead was once distributed in the Murray, Darling and Murrumbidgee rivers with the main stronghold being sections of the Murray River from Kerang to Swan Hill and down the Murray to the lower lakes.  The species has not been recorded very far up the Darling River (if at all) and not far up the Murrumbidgee with no recent verified records.  Populations in the Murray have become isolated with four genetically distinct management units.

Distribution decline in Victoria

 

 

 

The above maps demonstrate the decline of Murray Hardyhead in Victoria. There was a significant reduction in its range since the Millenium drought (1997 to 2009) which has resulted in genetically isolated populations.

The record in the Yarra River is an old unconfirmed record and most probably a miss identification.

Ecology & Habitat

Habitat

Historically, Murray Hardyhead would have been a flood dispersing species where they would have survived on the fringes of the flood plain in isolated wetland systems that became salty. During a flood these systems would have reconnected allowing dispersal.

Most records come from salty lakes, irrigation basins, creeks, rivers and drainage channels with salinity up to 110,000EC in areas containing submerged vegetation e.g. Ruppia Sea tassel. The Murray Hardyhead has not been recorded from the main part of the Murray River for many years.

Life span

Murray Hardyhead is a short-lived species less than two years old. They are regarded as an annual species which needs to reproduce each year for the population to persist.

Breeding

Breeding takes place during Spring/Summer, eggs are sticky and deposited on aquatic vegetation such as Rupia, peak hatching takes place in November.  After spawning during December and January many of the adults die off and the population declines. When conditions are ideal there can be a second Autumn spawning from the previous November spawning.

Diet

Mainly Zooplankton and micro-invertebrates e.g. midge larvae, mosquito larvae.

Population Status

The Murray Hardyhead has suffered a severe decline in recent years. In 2000 there were approximately 17 known populations in Australia, by 2014 only 5 populations remained. A major reason for the decline is attributed to the Millenium drought (1997-2009) in which resulted in low water levels and degraded fish habitat. There are grave concerns for the species when the next drought occurs.

The conservation status of Murray Hardyhead was raised from Vulnerable to Endangered in 2012 under the Commonwealth EPBC Act 1999. In Victoria, Murray Hardyhead is Listed as Critically endangered under the Victorian Flora & Fauna Guarantee Threatened List (FFG Threatened list 2024). Murray Hardyhead is also considered Critically endangered in New South Wales and South Australia.

The Australian Society for Fish Biology considers Murray Hardyhead to be Critically Endangered. Internationally, this species is also considered Critically endangered under the IUCN Red List (2025).

Threats

Changes to natural river flows 

Lack of regular flows with sufficient enough volume to reconnect fringing wetlands on the Murray floodplain with the main river.  Under natural conditions, the Murray River tended to be a low flowing river with periodic floods that filled areas which naturally became salty over time (favouring the Murray Hardyhead), the connectivity and reproduction habitat have since changed forcing the Murray Hardyhead to compete in less suitable habitats.

Weirs are barriers

Structures can impede dispersal; they can also permanently alter fringing wetlands upstream of the weir by reducing salinity which favours introduced species which are normally excluded in more saline wetlands. In altered conditions introduced species such as carp, redfin and mosquito fish Gambusia can easily out compete the Murray Hardyhead.

A full description of threats can be found in the National Recovery Plan.

Conservation & Management

There is a National Recovery Plan for Murray Hardyhead, produced in 2008  (DCCEWW (2025).  The plan is essentially aimed at improving the status of Murray Hardyhead by preserving the known populations and increasing its areas of occupancy. 

The recovery plan does not guarantee funding for the necessary actions and because the Murray Hardyhead is such a short-lived species there is a high risk of dramatic population decline occurring while implementation of the recovery process is being carried out.

Key conservation measures

• Environmental watering to maintain priority populations in identified wetlands whilst ensuring high enough salinity levels are maintained.
• Captive maintenance of rescued fish from populations at imminent risk.
• Captive breeding (can be expensive and difficult).
• Translocation to suitable habitats to reduce the risk of catastrophic loss.
• Translocation to surrogate dams which have been prepared and managed to support Murray Hardyhead. This also provides a source of fish for re-stocking to natural habitats and is more cost effective than captive management in tanks.
• Monitoring of status/threats of primary and secondary populations.

Projects & Partnerships

Saving our native species project – Murray Hardyhead

The Nature Glenelg Trust (NGT) has been working on conservation of the Murray Hardyhead for some years with cross-border partners. In 2024, NGT partnered with Millewa Pumping to lead a new project funded through the Australian Government’s Saving Native Species Program. The  aim is to prevent the extinction of Murray Hardyhead by protecting the few remaining wild populations and establishing backup populations in surrogate wetlands like farm dams or constructed ponds. Back-up populations are a critical contingency when species persist at only a few sites, as the risk of extinction is high. This project includes the continued coordination of the National Murray Hardyhead Recovery Working Group, monitoring at some of the persisting wild and surrogate populations, and securing environmental water supply for known populations. The team is also identifying future translocation opportunities to reinstate the Murray Hardyhead into suitable natural sites across its former range.

This project is funded by the Federal Government’s Saving Native Species Program.

This project is lead by NGT, and coordinated by NGT and Millewa Pumping Company, with many other collaborating organisations contributing to the project.

Saving Our Native Species - video highlighting the conservation of one of Australia's most threatened fish (Murray Hardyhead) - Nature Glenelg Trust.

Research

The Murray Darling Freshwater Research Centre undertook research into the Murray Hardyhead from 2004 to 2018 and has since been changed to the Centre for Freshwater Ecosystems (CFE).

Earlier research was conducted by Arthur Rylah Institute in the Kerang area. ARI also conducted an experiment to induce spawning in wild-caught adult fish, and expose the early life stages to varying levels of salinity, something that hasn’t been attempted for this species before. Manipulation of water temperature and light has been successfully used to promote multiple spawning’s in adults and shed new light on the species life history. The project has led to improvements in the hatching success of eggs, and the response of larvae and juveniles to varying levels of salinity which assists in the re-establishment of the species. ARI Research, Salinity tollerance fact sheet  pdf

Research to promote the recovery of the threatened Murray Hardyhead in the Lower Murray region of the Murray-Darling Basin was carried out with the translocation of 780 Murray Hardyhead from the Riverland region of South Australia to an environmentally watered floodplain wetland in far-west NSW in 2018. Follow up monitoring was carried out between 2019-2020 (Ellis et al. (2021).

Further information on the ecology of the Murray Hardyhead can be found in Koehn et al. (2020) which contains knowledge collated from over 600 publications and 27 expert workshops on covering

References & Links

ALA (2025) Atlas of Living Australia.

DCCEWW (2025) Backhouse, G., Lyon, J. and Cant, B. 2008a. National Recovery Plan for the Murray Hardyhead Craterocephalus fluviatilis. Department of Sustainability and Environment, Melbourne

DCCEEW (2025) Species Profile and Threats database – Murray Hardyhead Depatment of Climate Change, Energy, Environment and Water. 

Ellis et al. (2021) Ellis, I. Walker, J. Whiterod, N. and Healy, S.  Monitoring of translocated Murray Hardyhead in Little Frenchmans Creek, Wingillie Station NSW Final Report 2021, Commonwealth of Australia’.

FFG Threatened List (2024) Flora and Fauna Guarantee Threatened List - FFG Threatened List,  Department of Energy, Environment and Climate Action (DEECA)

IUCN (2025) Stoessel, D., Ellis, I.M., Whiterod, N., Gilligan, D., Wedderburn, S.D. & Bice, C. 2019. Craterocephalus fluviatilis. The IUCN Red List of Threatened Species 2019: e.T40692A123379212. https://dx.doi.org/10.2305/IUCN.UK.2019-3.RLTS.T40692A123379212.en. Accessed on 04 February 2025. https://www.iucnredlist.org/species/40692/123379212

Koehn et al. (2020) A compendium of ecological knowledge for restoration of freshwater fishes in Australia’s Murray–Darling Basin. Marine and Freshwater Research 71(11) 1391-1463 https://doi.org/10.1071/MF20127 Published: 9 October 2020.

VVB (2025) Visualising Victoria's Boidiversity - map portal

See reports:

Koehn 2021 - Key steps to improve the assessment, evaluation and management of fish kills: lessons from the Murray–Darling River system, Australia

Koehn et al. 2020 - A compendium of ecological knowledge for restoration of freshwater fishes in Australia’s Murray–Darling Basin

Ellis et. al 2013 - Conservation of an inauspicious endangered freshwater fish, Murray hardyhead (Craterocephalus fluviatilis), during drought and competing water demands in the Murray–Darling Basin, Australia

Murray Hardyhead Final Report 2005 - Ecology and breeding seasonality of the Murray hardyhead Craterocephalus fluviatilis (McCulloch), Family Atherinidae, in two lakes near Mildura, Victoria

SWIFFT Seminar notes – Murray Hardyhead conservation, February 2015

Please contribute information regarding Murray Hardyhead in Victoria - observations, images or projects.  Contact SWIFFT