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Murray Hardyhead (Craterocephalus fluviatilis)

The Murray Hardyhead is a small, schooling fish of the lowland Murray and lower Murrumbidgee systems in New South Wales, Victoria and South Australia. On works sites, clearing, dewatering, altered flows, poor water quality and damage to aquatic vegetation can kill fish or remove breeding habitat. It is listed as Endangered under Commonwealth legislation and Critically endangered in Victoria.

Conservation status

Commonwealth, EPBC Act 1999: Endangered.

Victoria, Flora and Fauna Guarantee Act 1988: Critically endangered.

Breeding season

Murray Hardyhead breeds in spring and summer. In Victorian wetlands, spawning extends from September to April and peaks in October and November, with larval abundance peaking in early November. Timing may vary between regions and with water levels, salinity and aquatic vegetation.

Breeding mode: Batch spawner. Eggs are laid among submerged aquatic vegetation, especially Ruppia beds.

Breeding season: September to April, with peak spawning in October and November.

Egg and larval habitat: Eggs attach to submerged vegetation. Widgeon grass and emergent vegetation are used where water levels are high enough to submerge the beds.

Breeding frequency: The species is considered primarily annual. Most fish mature, spawn and die within one year, and few survive into a second year.

Clutch or egg number: Not recorded.

Incubation period: Not recorded.

Age at maturity: Not recorded.

Breeding success varies between years and regions, especially with water levels, salinity, water quality and the availability of Ruppia and other submerged vegetation.

  • Adult breeding and spawning: Spawning occurs from September to April and peaks in October and November.
  • Eggs and larvae in aquatic vegetation: Eggs are attached to submerged vegetation, and larval abundance peaks in early November in Victorian lake populations.
  • Adult activity and habitat use: Murray Hardyhead is a mobile schooling fish that uses shallow wetland and lake-edge habitat, often around submerged vegetation.
  • Local recolonisation and dispersal: Movement between connected wetlands can occur when rainfall or increased water availability reconnects suitable habitat, but no regular seasonal migration is documented.
  • Highest clearing risk: Avoid clearing, dewatering and disturbance of occupied wetlands from September to April because eggs, larvae and newly recruited fish may be present in submerged vegetation.

Identification: Appearance and size

The Murray Hardyhead is a small, mobile schooling fish with a translucent, silvery body. Identification can be difficult where other hardyheads occur, so suspected records should be handled carefully and confirmed by an experienced fish ecologist.

Adults grow to about 75 mm total length. The back may be silver, silvery green, dark gold or golden, with a bright silver to silvery black mid lateral stripe and a pale abdomen.

The species has two separate dorsal fins. The first has 4 to 7 spines. The second has one spine and 5 to 8 rays. The anal fin is opposite the second dorsal fin and has one spine and 6 to 9 rays.

Transverse scales: Usually 10 to 12, including 4 to 8 above the mid lateral band.

Mid lateral scales: 31 to 35.

  • Small, protrusible mouth.
  • Large, silvery eye.
  • Forked caudal fin.
  • Thin, relatively small scales.
  • Fins may develop an orange sheen during spawning.

Identification: Similar species

The Murray Hardyhead has been confused with the Darling River Hardyhead, Lake Eyre Hardyhead and Unspecked Hardyhead. It can also occur with the Small mouthed Hardyhead in the lower Murray and Lower Lakes.

The Unspecked Hardyhead overlaps most often in the Murray Darling system. The Murray Hardyhead generally has smaller scales and more scales in the transverse series. Published keys may not always give a confident identification, so retain suitable specimens or photographs only under the direction of the relevant wildlife authority and project ecologist.

Potentially confusing species: Darling River Hardyhead, Lake Eyre Hardyhead, Unspecked Hardyhead and Small mouthed Hardyhead.

  • Use an experienced fish ecologist where Murray Hardyhead and Unspecked Hardyhead may occur together.
  • Take clear photographs of the whole fish and scale pattern where handling is permitted.
  • Record the exact waterbody, habitat, salinity and vegetation at each suspected detection.

Identification: Calls and field signs

No distinctive call or echolocation feature is used to locate this fish. Visual searches are unreliable because the fish are small and commonly occur among vegetation or turbid water.

There are no useful droppings, nests, whitewash, stains or odours to search for. The most useful field signs are a school of small silvery fish in shallow vegetated water, and the presence of suitable aquatic vegetation with recent inundation.

  • Look for small schools along sheltered edges and among submerged plants.
  • Do not treat a lack of visible fish as evidence of absence.
  • Use low impact trapping, scoop nets or other approved methods when a targeted survey is required.

Distribution: States and regions

The Murray Hardyhead is endemic to the lowland Murray Darling river system in south eastern Australia. Its former range was much wider, but current populations are scattered and isolated.

The species has been recorded in New South Wales, Victoria and South Australia. New South Wales records include the Darling River near Wentworth and the Murrumbidgee River at Narrandera, but it is considered extinct in the state based on the very limited recent record history.

In Victoria, confirmed populations have included wetlands near Swan Hill and Mildura. Extant sites identified in recovery planning include Round Lake, Woorinen North Lake, Cardross Lakes and Lake Hawthorn, although the status of individual sites can change with drying and water quality.

South Australia contains populations from the middle and lower Murray to the Lower Lakes. Records include the Berri and Dishers Creek evaporation basins, the Finniss, Angas and Marne rivers, Scotts Creek, Lake Albert, Lake Alexandrina and Hindmarsh Island.

  • Middle and lower Murray River floodplains.
  • Lower Lakes, including Lake Alexandrina and Lake Albert.
  • Isolated saline wetlands and evaporation basins.
  • Northern Victorian wetlands near Swan Hill and Mildura.

Distribution: Current distribution is fragmented

Populations may be separated by dry wetlands, unsuitable salinity, poor water quality or loss of aquatic vegetation. A nearby historical record does not confirm that a population remains at a site.

Identification uncertainty also affects older records. Treat historical locations and connected wetlands as potential habitat until a suitably designed survey has assessed them.

Overseas range: None. The Murray Hardyhead is endemic to Australia.

  • Check current biodiversity records before works begin.
  • Search connected wetlands, channels, backwaters and recently inundated habitat, not only the construction footprint.
  • Map all waterbodies that could receive pumped water, sediment or contaminated runoff.

Distribution: Site planning

For a project in the known range, assume that suitable shallow, vegetated water may support the species until a targeted assessment demonstrates otherwise. This approach is especially appropriate for Endangered and Critically endangered populations.

Engage the project ecologist and relevant state and Commonwealth regulators early where habitat clearing, dewatering, dredging, isolation or changes to water levels are proposed.

  • Confirm the legal approval pathway before disturbing aquatic habitat.
  • Plan surveys before water levels, vegetation or access conditions change.
  • Keep a clear record of survey conditions, effort, captures, releases and any unexpected detections.

Habitat: Waterbodies and landforms

The Murray Hardyhead uses shallow lakes, wetlands and riverine habitats across lowland floodplains. It is often associated with slightly to moderately saline water and submerged aquatic vegetation.

Search shallow margins of lakes, billabongs, backwaters, drainage wetlands, evaporation basins and off river floodplain wetlands. The species can also occur in sheltered edges of the Murray River, lower tributaries and the Lower Lakes.

Suitable habitat may be partly or fully isolated from the main river channel. Connected or intermittently connected wetlands can also provide habitat, particularly where submerged plants are dense.

Typical depth: Usually less than 0.5 m in documented habitat types.

Salinity: Documented habitat types range from 0.4 to 20 ppt, with the species tolerating a much wider range under some conditions.

  • Shallow, slow flowing or still water.
  • Sheltered lake and wetland margins.
  • Floodplain depressions and deflation basin lakes.
  • River backwaters and lower tributary wetlands.
  • Artificial saline wetlands and drainage basins.

Habitat: Aquatic vegetation

Look for submerged beds of Ruppia, Myriophyllum and Ceratophyllum. Ruppia, often called widgeon grass, is especially associated with saline wetland populations and provides cover, egg attachment sites and habitat for food organisms.

Dense vegetation is not required at every location, but loss or thinning of submerged plants can reduce cover and breeding opportunities.

  • Ruppia spp., including widgeon grass.
  • Myriophyllum spp., or water milfoil.
  • Ceratophyllum, or foxtail.
  • A mosaic of open shallow water and submerged plant beds.

Habitat: Water quality and hydrology

Habitat condition can change quickly. Drying, extreme salinity, low oxygen, nutrient enrichment, algal blooms and unsuitable pH have been associated with population losses.

Maintain natural or agreed water levels and connections where possible. Prevent sediment, polluted runoff, acidic drainage and construction chemicals from entering occupied or potential habitat.

  • Inspect water level, clarity, salinity, temperature and aquatic vegetation before works.
  • Identify acid sulphate soil risks before excavation or drawdown.
  • Keep access tracks, stockpiles and spoil away from wetland edges and drainage paths.

Foraging habitat: Food resources

Murray Hardyheads feed in shallow water among submerged vegetation and along sheltered margins. Their main food is zooplankton, so water level and plant condition affect both feeding and recruitment.

The diet includes zooplankton, dipteran larvae and pupae, algae and other small aquatic organisms. Zooplankton are a major food source, and many small crustaceans use Ruppia beds as habitat.

Avoid sudden changes that remove shallow feeding areas or expose vegetated sediments during the breeding season.

  • Submerged Ruppia, Myriophyllum and Ceratophyllum beds.
  • Shallow inundated sediments supporting zooplankton.
  • Sheltered edges with a mix of open water and vegetation.
  • Low disturbance areas away from strong flows and heavy machinery.

Foraging habitat: Works site considerations

Dewatering, rapid drawdown, sediment disturbance and poor water quality can reduce food resources and strand fish. Pumped water can also transfer fish, eggs, sediment or contaminants between wetlands.

Use screened pumps and an approved fish rescue and relocation plan where dewatering cannot be avoided. Do not move captured fish between waterbodies without regulatory approval.

  • Stage drawdown slowly where approvals allow.
  • Use screens and check them frequently to prevent fish entrainment.
  • Treat discharge water before release and prevent turbid or saline plumes.
  • Inspect isolated pools and shallow margins before they are drained.

Breeding habitat: Breeding places and timing

The Murray Hardyhead is an annual species in which successful recruitment each year strongly affects population persistence. It lays eggs among submerged aquatic vegetation, especially Ruppia, during an extended spring and summer breeding period.

Spawning occurs from September to April and peaks in October and November. Eggs are attached among submerged vegetation, including Ruppia, with emergent vegetation and suitable water levels also associated with spawning habitat.

Protect vegetated shallow margins throughout the breeding period. Because eggs and larvae are small, assume that disturbance to an occupied plant bed may affect more than the adult fish seen during a survey.

Breeding period: September to April, with peak spawning in October and November.

Larvae: Newly hatched larvae as small as 5 mm have been collected in mid summer.

  • Inundated Ruppia beds.
  • Shallow vegetated lake and wetland margins.
  • Edges where submerged and emergent vegetation meet.
  • Recently refilled wetlands with suitable submerged plants.

Breeding habitat: Recruitment risks

Drying, extreme salinity, unstable oxygen levels, algal blooms and loss of submerged plants can cause recruitment failure. A short period of poor conditions can affect the whole annual population because few fish survive into a second year.

Keep breeding habitat wet and connected where feasible, while avoiding unapproved water transfers that could spread fish, disease or contaminants.

  • Schedule unavoidable in water works outside the breeding period where practicable and where this is consistent with approvals.
  • Retain submerged vegetation and avoid dragging machinery or nets through plant beds.
  • Monitor water levels and water quality during works and after refilling.
  • Report unexpected fish, eggs or larvae immediately to the site ecologist.

Breeding habitat: Survey approach

Targeted surveys should cover shallow vegetated margins and likely spawning habitat. Use methods suited to small fish and minimise habitat disturbance, with additional care during September to April.

A survey should record effort, water conditions, salinity, vegetation, bycatch and all hardyhead identifications. Confirm difficult records with an experienced taxonomist or fish ecologist.

  • Use approved scoop nets, small traps or other low mortality methods.
  • Avoid seine netting where it would damage littoral or submerged vegetation.
  • Inspect nets and traps frequently and keep temporary holding time short.
  • Follow animal ethics, fish handling and biosecurity requirements.

Sheltering habitat: Shelter features

Submerged aquatic vegetation provides cover from predators and shelter from local water movement. Saline wetlands can also offer refuge because they exclude many less salt tolerant native and introduced fish.

Look for Ruppia beds, dense Myriophyllum or Ceratophyllum, shallow vegetated edges and sheltered pockets. Open shallow water beside dense plants can also be used by schools.

Do not clear aquatic vegetation simply to improve access or visibility. Retain a connected mosaic of plant beds, open water and undisturbed margins.

  • Dense submerged macrophytes.
  • Sheltered wetland and lake edges.
  • Shallow backwaters and billabongs.
  • Vegetated channels and recently inundated areas.

Sheltering habitat: Protection during works

Fish may shelter in vegetation, shallow pools and isolated wetland margins during low flows or falling water levels. They can be injured by pumps, vehicles, sediment, nets and sudden changes in water quality.

Fence or otherwise mark exclusion areas around occupied habitat. Keep machinery, refuelling, spoil and washdown activities outside wetland margins and drainage paths.

  • Use screened low impact pumps where pumping is approved.
  • Provide a fish rescue procedure before isolating or draining water.
  • Maintain water quality and avoid rapid changes in salinity or oxygen.
  • Clean equipment between waterbodies to reduce disease and pest transfer.

Threats: Dewatering and altered water levels

The Murray Hardyhead has lost much of its former range and now persists in isolated populations. Works that alter water, vegetation or connectivity can have serious effects, particularly in Victoria where the species is Critically endangered.

Wetland drying, rapid drawdown and reduced river flows can remove habitat, expose fish to predators and prevent eggs from remaining submerged. Construction pumping, levees, culverts and temporary crossings can create similar effects.

Avoid draining or isolating potential habitat unless the action is approved and a fish rescue plan is in place. Maintain suitable water levels and connections where required by the project approval.

  • Map all inflows, outflows and low points before earthworks.
  • Use staged drawdown where practicable.
  • Check isolated pools, plant beds and damp depressions before they dry.
  • Keep emergency response arrangements in place during pumping and refilling.

Threats: Water quality and salinity

Sediment, nutrients, acid sulphate soil drainage, contaminants, algal blooms, low oxygen and unsuitable pH can make a wetland uninhabitable. Salinity can change rapidly when water levels fall or saline drainage is altered.

Use erosion and sediment controls, isolate dirty water and monitor discharge points. Do not assume that a saline wetland is too harsh for the species.

  • Prevent turbid runoff from entering habitat.
  • Manage saline spoil and groundwater appropriately.
  • Monitor for fish distress, odours, surface films, algal blooms and sudden changes in water condition.
  • Stop and notify the site ecologist if unexpected impacts occur.

Threats: Vegetation loss and physical disturbance

Clearing or damaging Ruppia and other submerged vegetation removes shelter, feeding habitat and egg attachment sites. Trampling, vehicle access, dredging and seine netting can disturb shallow margins and sediments.

Keep machinery out of aquatic plant beds and retain habitat buffers or exclusion zones specified by the approval. Use low impact survey methods and avoid unnecessary handling.

  • Mark aquatic vegetation before works start.
  • Use existing access routes where possible.
  • Do not drag nets or hoses through plant beds.
  • Rehabilitate disturbed margins with locally appropriate aquatic vegetation where directed by the ecologist.

Threats: Predation, competition and fragmentation

Introduced fish such as Eastern Gambusia can compete with or prey on native fish. Loss of connectivity can prevent recolonisation, while moving water, fish or equipment between sites can spread pests and disease.

Treat every population as a separate conservation asset unless approved genetic or translocation planning says otherwise. Any relocation, captive breeding or translocation must be led by the relevant authorities and qualified specialists.

  • Prevent unauthorised fish movement between wetlands.
  • Inspect pumps, nets, buckets and vehicles before moving between sites.
  • Report introduced fish and unusual mortality promptly.
  • For Endangered or Critically endangered populations, use a precautionary approach and stop works if unplanned harm is likely.

Survey methodology: 1. Desktop assessment

Survey for Murray Hardyhead in shallow, sheltered wetland margins, billabongs, backwaters and saline lakes. Plan surveys around low-flow conditions and repeat them where habitat is suitable, because the species is mobile, schooling and easily confused with other hardyheads.

Map all wetlands, channels, billabongs, backwaters and drainage basins that may be connected to the work area. Give priority to shallow water less than 0.5 m deep, submerged vegetation and salinities from slightly saline to highly saline.

Check historical records, recent habitat condition, water levels, salinity, connectivity and records of Unspecked Hardyhead, Small-mouthed Hardyhead and other similar fish. Treat old records cautiously because hardyhead species were historically confused.

Breeding season: September to April, with spawning peaking in October to November

Typical habitat depth: Less than 0.5 m

Common vegetation association: Submerged *Ruppia* and other aquatic plants

  • Identify *Ruppia*, milfoil, foxtail and other submerged vegetation before selecting survey points.
  • Map inflows, outflows, culverts, temporary connections and areas that could dry or become isolated during works.
  • Seek advice from the relevant state agency and a fish ecologist where identification is uncertain.

Survey methodology: 2. Select suitable survey conditions

Survey sheltered edges, shallow open water and dense aquatic vegetation. Include both saline and slightly saline habitats, as Murray Hardyhead uses a broad salinity range.

In Victoria, lower-flow conditions from December to April can improve capture chances. In southern states, drier conditions from March to May may also assist detection. Avoid relying on a single visit where water levels, salinity or connectivity are changing.

Survey before vegetation is removed, water is pumped down or a wetland is isolated.

  • Record water depth, salinity, conductivity, temperature, pH, dissolved oxygen, turbidity, water level and recent rainfall where practicable.
  • Record aquatic vegetation type, density, extent, submerged or exposed condition, woody debris and bank characteristics.
  • Document whether the site is connected to a river, channel or neighbouring wetland.

Survey methodology: 3. Use low-impact capture methods

Use small scoop or dip nets, bait traps and, where suitable, backpack electrofishing. Combine methods when vegetation, depth or water quality limits the effectiveness of one method.

Set collapsible bait traps with approximately 3 mm mesh for 30 to 60 minutes. Check traps thoroughly and frequently enough to minimise stress and predation.

Use fine mesh seines only where electrofishing and trapping are unsuitable. Seine carefully through vegetation because seine use can disturb habitat and cause fish mortality.

Trap size described for group surveys: Approximately 250 x 250 x 450 mm

Seine mesh described for group surveys: 2 to 5 mm

Preferred handling approach: Use dip nets and minimise scale loss and time out of water

  • Use backpack electrofishing only in wadeable still water or shallow flowing water, under the applicable code of practice and by trained operators.
  • Where electrofishing is used with a seine, secure the fine mesh net downstream and collect stunned fish with dip nets.
  • Keep captured fish in a bucket partly filled with site water while they are identified and processed.
  • Release fish at the capture location as soon as processing is complete, unless an authorised rescue or translocation is underway.

Survey methodology: 4. Confirm identification and record effort

Have an experienced fish ecologist confirm Murray Hardyhead where Unspecked Hardyhead, Small-mouthed Hardyhead or other similar species occur. Do not rely on a single field character when the identification may affect a clearing decision.

Record photographs, voucher information where authorised, diagnostic features, measurements, sex or maturity if assessed, and the fate of every captured fish. Genetic or morphometric confirmation may be needed for difficult records.

Record negative results as well as captures. A negative result does not demonstrate absence if habitat was inaccessible, water levels were unsuitable or survey effort was limited.

  • Record date, start and finish time, surveyors, method, gear dimensions, number of sets or passes and the area or bank length searched.
  • Record all native and introduced fish captured, including Eastern Gambusia and Carp Gudgeon.
  • Map every capture and all breeding habitat, submerged vegetation and potential refuge areas.
  • Report records promptly to the project ecologist and relevant fauna authority.

Before habitat disturbance: 1. Confirm approvals and permits

Avoid wetland and aquatic vegetation impacts wherever practicable. Confirm the legal pathway before work starts, then use targeted surveys and site controls to protect fish, eggs, larvae and annual recruitment.

Assess whether the action may affect a nationally listed endangered species or its habitat. Refer the action under the EPBC Act if the project may have a significant impact on Murray Hardyhead or its habitat.

Obtain all required state or territory threatened species, fisheries, wildlife, collection, handling and translocation approvals before surveying, rescuing or moving fish.

If work is proposed in Queensland, confirm whether a species management program is required for interference with a breeding place. Although Murray Hardyhead is mapped in New South Wales, Victoria and South Australia, apply the relevant local legal pathway to the actual work site.

  • Check approval conditions for survey methods, aquatic fauna handling, salvage, release locations, reporting and independent supervision.
  • Use only authorised people for capture, handling, identification, rescue and translocation.
  • Keep copies of approvals, permits, method statements and contact details at the work site.

Before habitat disturbance: 2. Avoid and protect habitat

Redesign the work to retain wetlands, shallow margins, submerged vegetation and connections between occupied or potential habitats. Avoid draining, isolating, filling or rapidly changing water levels.

Protect *Ruppia*, milfoil, foxtail and other submerged plant beds. These areas provide cover, food resources and egg attachment sites.

Prevent sediment, nutrients, contaminated water, concrete washout, fuels and other pollutants from entering the wetland.

  • Use a no-go area around occupied habitat and breeding vegetation, with the extent set by the project ecologist and approval conditions.
  • Fence exclusion areas before plant arrives and mark them clearly on plans and in the field.
  • Keep pumps, access tracks, spoil, refuelling areas and stockpiles outside aquatic habitat and drainage paths.
  • Maintain water quality, water levels and connectivity for the duration of the works.

Before habitat disturbance: 3. Complete pre-clearance checks

Survey the entire impact area and connected aquatic habitat before dewatering, vegetation removal, bank works or construction. Include shallow margins and dense submerged vegetation that may be missed by a visual inspection.

Schedule checks during the September to April breeding season where works could affect spawning vegetation, eggs or larvae. Recheck immediately before impact if water levels, connectivity or the work footprint changes.

Use an aquatic fauna ecologist to assess whether a rescue, staged drawdown or other approved management response is required.

  • Inspect for Murray Hardyhead and other threatened fish using approved capture methods, not visual inspection alone.
  • Identify spawning habitat, including submerged *Ruppia* and emergent vegetation that may become inundated.
  • Check pumps, culverts, cofferdams and isolated pools for trapped fish before they are started, moved or removed.
  • Document the pre-clearance condition with maps, photographs, water quality results and survey records.

Before habitat disturbance: 4. Induct the crew and prepare controls

Brief all workers, operators, fauna spotter catchers and subcontractors before entering the site. Explain the species appearance, habitat, exclusion areas and stop-work process.

Nominate one person with authority to stop work. Make that authority clear to the supervisor, plant operators and all subcontractors.

Prepare clean equipment and biosecurity controls to prevent movement of fish, eggs, pathogens, weeds and contaminated water between wetlands.

  • Show workers how to recognise a small silvery or golden fish with a silver mid-lateral stripe and a forked tail.
  • Tell workers not to handle fish, disturb aquatic vegetation or move water unless authorised.
  • Keep rescue containers, aeration equipment, dip nets, shade and clean site water available where approved fauna handling may be needed.
  • Include emergency contacts, permit conditions and the injured animal pathway in the induction.

During habitat disturbance: 1. Use staged, sequential clearing

Work from low-risk areas towards higher-risk aquatic habitat and keep impacts controlled. Stop work immediately when a Murray Hardyhead, suitable breeding habitat or an unexpected aquatic fauna issue is found.

Clear terrestrial vegetation and access areas first. Keep aquatic works, dewatering and submerged vegetation removal until the fauna ecologist has completed the required checks and controls.

Use staged drawdown or isolation where approved, rather than sudden dewatering. Retain water, shade and aquatic vegetation for as long as practicable.

Maintain escape routes to retained habitat until the authorised fauna team confirms that the work area is clear.

  • Start at the downstream or outer edge only where the approved method requires it and where fish will not be trapped or pushed into the impact area.
  • Check isolated pools, channels, pump intakes, culverts and wet vegetation after each stage.
  • Keep machinery out of exclusion zones and prevent sediment or polluted water from entering retained habitat.
  • Stop if water levels, salinity, oxygen or turbidity change outside the approved limits.

During habitat disturbance: 2. Stop work and manage a find

The fauna spotter catcher or aquatic fauna ecologist must have authority to stop work. Stop immediately if Murray Hardyhead, eggs, larvae, a concentrated group of fish or suitable active spawning habitat is found within the impact area.

Keep people, plant and pumps clear of the location. Do not chase, net or move fish until the authorised person confirms the response.

Treat submerged *Ruppia* and other vegetation with attached eggs as breeding habitat and protect it until the project ecologist and regulator agree on the next step.

  • Mark the location and establish a temporary exclusion area.
  • Notify the site supervisor, project ecologist and relevant approval contact.
  • Photograph and map the find without disturbing it.
  • Resume only under a documented response approved by the responsible ecologist and relevant authority.

During habitat disturbance: 3. Handle and relocate fish safely

Only authorised and trained people may capture, identify, hold, transport or release Murray Hardyhead. Handle fish gently because the species is small and delicate and can lose scales during capture.

Use clean, aerated containers partly filled with water from the capture site. Keep fish shaded and minimise handling time.

Do not translocate fish to another wetland unless the action is specifically approved, the source and destination populations are suitable, and disease and genetic risks have been assessed.

  • Use dip nets rather than grasping fish by hand.
  • Separate fish from predators and introduced fish where practicable during temporary holding.
  • Maintain records of capture location, number, condition, holding time, release location and the person responsible.
  • Release fish only at the approved location and under the approved method.

During habitat disturbance: 4. Respond to injured or dead animals

Stop the immediate cause of harm and notify the fauna ecologist. Do not release an injured fish without advice from the authorised aquatic fauna specialist.

Place a live injured fish in clean, aerated site water and keep it shaded while the specialist arranges assessment or an approved release response.

Treat dead or moribund fish as an incident, particularly if more than one fish is affected.

  • Record the species, number, condition, location, time, likely cause and photographs.
  • Notify the relevant regulator where required by the approval or permit.
  • Preserve specimens only under the direction of an authorised person and applicable permit.
  • Check pumps, water quality, sediment, chemicals and exclusion controls before restarting work.

After habitat disturbance: 1. Complete post-clearance checks

Do not treat completion of clearing as the end of fauna management. Confirm that the work area is clear, report all outcomes and check whether retained habitat and relocated fish remain viable.

Inspect the full impact area after plant and pumps are removed and again after water levels stabilise. Check isolated pools, wet vegetation, culverts, drains, pump infrastructure and sediment traps.

Look for live or dead fish, stranded larvae, eggs attached to vegetation, drying habitat, polluted water and barriers to movement.

Have the aquatic fauna ecologist sign off the area before the site is released from fauna controls.

  • Record the date, people involved, areas checked, methods used and results.
  • Remove temporary barriers only when the project ecologist confirms that doing so will not drain or isolate retained habitat.
  • Repair leaks, blocked connections, damaged exclusion fencing and erosion controls promptly.
  • Retain photographs and maps that show the final condition.

After habitat disturbance: 2. Report and close out the work

Prepare the required report for approval holders, regulators and land managers. Include both positive and negative survey results and explain any departure from the approved method.

Report any capture, relocation, injury, death, breeding habitat impact, water quality event or unauthorised disturbance within the required timeframe.

Provide records to the relevant recovery or land management program where requested.

  • Include survey effort, water conditions, capture data, identification checks and fate of all animals.
  • Include maps of occupied habitat, exclusion areas, impact areas, release sites and restored areas.
  • Record permit numbers, approval conditions, incidents, corrective actions and responsible people.
  • Store data in a format that can be used for future monitoring and site planning.

After habitat disturbance: 3. Monitor relocated and retained populations

Monitor relocated fish and retained habitat under the translocation approval and project monitoring plan. Use the same or comparable methods at each visit so changes can be interpreted.

Check recruitment, adult presence, aquatic vegetation, water levels, salinity, dissolved oxygen, connectivity and introduced fish. Annual recruitment is especially important because Murray Hardyhead is generally considered an annual species.

Use a qualified fish ecologist to review results and adjust water management or follow-up actions.

  • Survey during suitable low-flow conditions and include the September to April breeding period where recruitment is an objective.
  • Check whether fish are using shallow margins and submerged vegetation, not only open water.
  • Record evidence of spawning, larvae, juveniles and successful recruitment where the method allows.
  • Do not use monitoring results to justify further translocation without the required approval.

After habitat disturbance: 4. Review incidents and improve controls

Hold a short review after the work and after any incident. Include the site supervisor, fauna spotter catcher, aquatic ecologist and relevant contractor.

Identify whether the survey detected fish, whether controls protected water quality and vegetation, and whether the work altered connectivity or water levels.

Update the construction environmental management plan and induction material before the next work stage or similar project.

  • Review plant access, pump placement, drawdown rate, lighting, sediment controls and exclusion fencing.
  • Check whether the timing avoided spawning and recruitment risks.
  • Record actions, owners and completion dates for every improvement.
  • Share lessons with land managers and approval holders.

Rehabilitation actions: 1. Restore aquatic habitat

Restore shallow, sheltered aquatic habitat rather than creating generic open water. The best rehabilitation outcome is a stable wetland with suitable salinity, submerged vegetation, water quality and connectivity that supports annual recruitment.

Reinstate shallow margins, sheltered backwaters and slow-flowing or still water. Retain a mix of open shallow water and dense submerged vegetation.

Re-establish *Ruppia* and other suitable aquatic plants using locally appropriate material and an approved biosecurity method. Protect newly planted beds from grazing, trampling, turbidity and sudden drawdown.

Restore natural or managed connections to nearby wetlands where this is compatible with the population, water regime and approval conditions.

  • Shape banks and shallow shelves to provide inundated vegetation habitat at suitable water levels.
  • Use clean, uncontaminated sediment and prevent acid sulfate soil exposure or runoff.
  • Remove or manage barriers that strand fish or prevent safe movement between connected habitats.
  • Do not introduce fish, aquatic plants or water from another catchment without approval and biosecurity assessment.

Rehabilitation actions: 2. Manage water and water quality

Maintain water levels that inundate submerged vegetation during the breeding season without causing prolonged stagnation or rapid drying. Manage salinity within the natural or approved range for the site.

Protect inflows and outflows from sediment, nutrients, chemicals, algal blooms and contaminated construction water. Monitor conditions during the first wet and dry periods after rehabilitation.

Use gradual changes in water level where practicable, particularly from September to April when spawning and recruitment occur.

  • Measure water level, salinity or conductivity, temperature, pH, dissolved oxygen and turbidity at agreed intervals.
  • Keep exposed sediments, acid sulfate soils and spoil out of the wetland and its drainage paths.
  • Maintain water to submerged *Ruppia* beds and other breeding vegetation during approved breeding periods.
  • Investigate fish stress, kills, sudden salinity change or algal blooms immediately.

Rehabilitation actions: 3. Provide breeding and shelter habitat

Murray Hardyhead attaches eggs to submerged aquatic vegetation, especially *Ruppia*. Restore and protect suitable plant beds instead of installing artificial nest structures.

Nest boxes, bat boxes, artificial nest sites and roost structures do not suit this fish. Do not install them as a substitute for submerged vegetation or suitable water conditions.

Use habitat complexity to provide cover from predators and support zooplankton and aquatic insects that form part of the diet.

  • Retain submerged vegetation through the spawning season where practicable.
  • Avoid removing vegetation from shallow margins during September to April unless the approved method requires it and authorised fauna advice has been obtained.
  • Monitor plant density, extent and condition as a rehabilitation outcome.
  • Control introduced predators and competitors under an approved aquatic pest management program.

Rehabilitation actions: 4. Control weeds, access and lighting

Control terrestrial and aquatic weeds without contaminating the wetland or damaging native submerged vegetation. Use methods approved for aquatic habitat and the target weed.

Limit vehicle access, trampling, stock access and recreational disturbance around shallow margins and plant beds.

Use low-spill, shielded lighting and switch off unnecessary lights at night. Avoid lighting wetlands, vegetation beds and movement corridors.

  • Clean machinery, nets, boats and footwear before entering another waterbody.
  • Remove weed material from the site or dispose of it under the approved biosecurity procedure.
  • Fence or sign sensitive rehabilitation areas until plants are established.
  • Inspect for new weeds, erosion, rubbish, artificial barriers and introduced fish during each monitoring visit.

Rehabilitation actions: 5. Monitor long-term success

Monitor the restored wetland for several breeding seasons, with the duration set by the approval and recovery objectives. Assess habitat and fish outcomes together because a vegetated wetland can still fail if water quality or recruitment is poor.

Use repeatable survey methods and compare results with nearby retained habitat or an approved reference site. Review management if Murray Hardyhead is absent, recruitment fails or habitat dries unexpectedly.

Keep monitoring active after construction risks have ended, particularly at isolated saline wetlands that depend on managed water levels.

  • Track Murray Hardyhead presence, abundance or catch rate, size classes, larvae or juveniles and annual recruitment.
  • Track *Ruppia* and other aquatic vegetation, water depth, salinity, oxygen, pH, turbidity and connectivity.
  • Track native and introduced fish, predation signs, algal blooms and drying or excessive salinity.
  • Report results to the approval holder, regulator and relevant recovery program, and document any change to water or vegetation management.

Sources