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Flathead Galaxias (Galaxias rostratus)

The flathead galaxias is a small, critically endangered freshwater fish of the southern Murray-Darling Basin. It uses still or slow-flowing rivers, billabongs, lagoons, wetlands, lakes and backwaters, so works that alter aquatic vegetation, floodplain connections, flow, water quality or fish passage can affect habitat and recruitment.

Conservation status

Commonwealth, EPBC Act 1999: Critically endangered.

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

Breeding season

The seasonal pattern below applies to the southern Murray-Darling Basin populations described in the supplied documents. Local timing may vary with water temperature, flooding and water management.

Clearing risk can occur in any month if works remove aquatic vegetation, disturb bottom habitat, alter flows, release sediment or pollutants, or block fish passage.

  • Breeding: Spawning occurs in August and September when water temperature rises above 10.5°C. Eggs are demersal and hatch after about 8 to 9 days.
  • Young and recruitment: Eggs and newly hatched larvae are expected after spring spawning. Larvae are about 5.7 to 8.1 mm at hatching. The documents do not define the full period of dependence.
  • Upstream movement: There are indications of upstream movement in November and December. The extent and purpose of this movement are poorly known.
  • Wetland connection and recruitment: Access to billabongs, lagoons and wetlands depends on flow regimes and inundation. Environmental watering or natural floods can support movement, breeding and recruitment, but no single monthly peak is established.
  • Highest clearing risk: Avoid clearing, dewatering, isolation and disturbance of occupied or connected aquatic habitat from August to December where practicable. This period includes spawning, early recruitment and the indicated upstream movement period.

Identification

Flathead galaxias is a small, slender galaxiid that usually schools in mid-water. Identification requires close examination because it overlaps with common galaxias and obscure galaxias.

The body is elongated and scaleless, with an olive-green to brown back and sides, a silvery belly, transparent fins and a forked tail. The head is distinctly flattened, the mouth is large and extends well below the eye, and the lower jaw may protrude slightly.

The anal fin begins almost directly below the dorsal fin and has a relatively long base. The dorsal fin origin is slightly in front of the anal fin origin. Fish may show pigment spots at the bases of the fin rays.

Maximum length: About 146 to 150 mm

Typical upper size: Rarely more than 100 mm

Maximum weight: 22.5 g

Identification: Distinguishing similar fish

Common galaxias, Galaxias maculatus, can look similar, but the flathead galaxias has a more obviously flattened head and a larger mouth. The lower jaw may protrude slightly in flathead galaxias.

Obscure galaxias, Galaxias oliros, overlaps in the Murray-Darling Basin. In flathead galaxias, the anal fin origin is almost directly below the dorsal fin origin. In obscure galaxias, the anal fin origin is distinctly behind the dorsal fin origin.

  • Photograph the whole fish from the side and record the head profile, mouth size, dorsal fin origin and anal fin origin.
  • Use an experienced freshwater fish identifier where the fish is small, damaged or viewed briefly in turbid water.

Identification: Field signs and handling

The species commonly forms shoals in mid-water. In low-oxygen conditions it may move to the surface and use the thin oxygenated boundary layer at the water surface.

There are no documented species-specific tracks, scats, calls, nests, burrows, hollows, sloughs or eyeshine. Presence is normally established by capture, visual observation or targeted environmental DNA surveys.

  • Treat any suspected individual as a threatened native fish and do not retain, move or handle it except under the relevant approval and an approved survey method.
  • Record the waterbody, exact location, date, habitat, water conditions, photographs and identification features.

Distribution: National range

Flathead galaxias is restricted to the southern half of the Murray-Darling Basin. Its former range was broad but patchy, and recent records are rare and irregular.

In New South Wales, historical records include the Lachlan, Murrumbidgee and Murray catchments, with isolated records from the Macquarie catchment near Bathurst. The species is presumed locally extinct from the Lachlan, Murrumbidgee, Macquarie and lower Murray catchments in New South Wales.

In Victoria, records include the Mitta Mitta, Kiewa, Ovens, Goulburn, Loddon, Murray, Broken, Avoca and Corop Lakes systems, including wetlands, billabongs and tributaries. In South Australia, there is an old record from the lower Murray, but the species has not been recorded there for more than 30 years and is considered absent.

The species is not recorded from Queensland or the Australian Capital Territory in the supplied sources. The broad bioregional setting is the southern Murray-Darling Basin, including its lowland rivers, floodplains and associated wetlands.

Distribution: Remaining records and strongholds

The species may persist in billabongs, dams, lagoons and other waterways in the upper Murray catchment. Recent records have also come from the Goulburn catchment and from Victorian waterways in the upper Murray and central Victoria.

Known recent locations include Cudgewa Creek, Normans Lagoon near Albury, the Yea River, a Goulburn billabong near Alexandra, Gap Creek in the Kiewa catchment, Sandy Creek in the Mitta Mitta catchment and upper Wanalta Creek. Only small numbers have generally been recorded, and occurrence is inconsistent.

A targeted Victorian survey of 60 sites detected the species at four sites, all in the Goulburn or upper Murray catchments. Detection can be difficult, so absence from a single survey does not establish local extinction.

Distribution: Population trend

The species has undergone a very severe decline. Historical accounts describe it as locally abundant in suitable habitats, whereas many later surveys found no individuals or only very small numbers.

The Sustainable Rivers Audit did not detect the species in sampling between 2004 and 2010, although that programme did not sample wetlands within river valleys. The MDB Fish account reports only two individuals from the Sustainable Rivers Audit between 2004 and 2013, followed by two more from the MDB Fish Survey between 2014 and 2021.

Historical area of occupancy: 84 km²

Historical extent of occurrence: 23,065 km²

Estimated population reduction used for EPBC assessment: More than 80 percent, based on direct observations over approximately the past 50 years

Recent Victorian targeted survey: Four detections from 60 sites

Habitat: Waterbodies and flow

Flathead galaxias occupies lowland and floodplain freshwater habitats, particularly still or gently flowing waters. It is associated with aquatic vegetation, soft or coarse substrates and connections between rivers and wetlands.

Recorded habitats include billabongs, lakes, swamps, lagoons, dams, backwaters, small streams, river channels and floodplain wetlands. The species generally prefers still or slow-flowing water and schools in mid-water.

Waterbodies may be connected to rivers during floods or managed inundation. Lateral connectivity between rivers, floodplains and wetlands is therefore an important habitat attribute.

Habitat: Vegetation and physical structure

Habitat may include aquatic vegetation such as ribbon weed, Vallisneria species, together with rock, sand, mud or coarse substrate. Loss of aquatic vegetation and siltation are identified threats.

Retain aquatic plants, vegetated wetland margins, backwaters and unobstructed connections between the main channel and floodplain wetlands during project planning and construction.

Habitat: Elevation and climate limits

The former New South Wales distribution was mainly in middle river reaches, usually below 150 m elevation. The supplied sources do not define a full temperature, rainfall or elevation limit for the species.

The species can respond to oxygen depletion associated with high temperatures, organic matter and water-column stratification by using the oxygen-rich surface boundary layer.

Foraging habitat: Diet

The flathead galaxias feeds in the waterbodies where it schools, mainly taking small aquatic prey. The available sources do not provide a measured foraging range or daily movement distance.

The diet consists predominantly of aquatic insects, with some microcrustaceans. The supplied sources do not identify particular insect taxa or plant foods.

Main food: Aquatic insects

Additional food: Microcrustaceans

Foraging habitat: Foraging locations and behaviour

Fish generally school in mid-water in still or slow-flowing streams, lakes, lagoons, billabongs, backwaters and wetlands. Aquatic vegetation and intact wetland habitat may support feeding and nursery functions.

No quantified home range, feeding radius or routine daily movement distance is available. A possible upstream movement period occurs in November and December.

  • Avoid isolating shallow wetlands, billabongs and backwaters from the river during works.
  • Prevent sediment, pollutants and construction runoff from entering aquatic insect habitat and wetland edges.

Breeding habitat: Breeding biology

Spawning occurs in spring in occupied freshwater habitat. Recruitment depends on suitable water temperature, connected or watered wetlands, and intact bottom habitat where demersal eggs settle.

Eggs are spawned randomly at multiple sites and settle on the bottom of the waterbody where adults occur. They are round, demersal and slightly adhesive.

Fecundity increases with fish length. Hatching occurs after about 8 to 9 days under reported water temperatures of 9 to 14°C. Individuals probably mature in their first year at about 80 mm.

Spawning season: August and September, when water temperature is above 10.5°C

Egg number: About 2,300 eggs in an 86 mm fish and about 7,000 eggs in a 136 mm fish

Egg type: Round, demersal and slightly adhesive

Egg diameter: 1.3 to 1.6 mm

Hatching time: About 8 to 9 days

Larval size at hatching: 5.7 to 8.1 mm, or about 6 to 8 mm in the NSW account

Age at maturity: Probably during the first year, at about 80 mm

Lifespan: Unknown

Gestation or incubation: No gestation. Egg development to hatching takes about 8 to 9 days.

Breeding habitat: Breeding habitat requirements

Spawning habitat includes the bottom of still or gently flowing streams, billabongs, lakes, lagoons, dams, wetlands and backwaters occupied by adults. Eggs may be distributed among several sites, reducing the chance that one local impact removes all eggs.

Environmental watering and natural flood events can provide access to off-stream billabongs, lagoons and wetlands for breeding, movement and recruitment. Barriers, altered flow timing and cold water releases can reduce spawning or recruitment success.

  • Protect occupied wetland margins, shallow backwaters, aquatic vegetation and bottom substrates from dewatering, infilling, sedimentation and direct disturbance during August to September.
  • Maintain fish passage and lateral connection between rivers and floodplain wetlands where project works affect regulators, levees, culverts, weirs or other barriers.

Sheltering habitat: Refuge features

No species-specific den, burrow, hollow or nest is used. Shelter and refuge are provided by persistent waterbodies, aquatic vegetation, wetland margins and connected backwaters.

Potential refuge habitat includes permanent or semi-permanent billabongs, lagoons, dams, lakes, wetlands, slow-flowing channels and backwaters that retain water and aquatic vegetation. The species has been associated with ribbon weed and with sand, mud or coarse substrates.

Fish generally school in mid-water. Eggs settle on the bottom, so both the water column and undisturbed bottom habitat can provide important refuge or breeding structure.

Sheltering habitat: Low-oxygen refuge behaviour

When oxygen levels decline, flathead galaxias may move to the surface and use the thin oxygenated boundary layer, usually within the top 1 mm of water. This behaviour is an adaptation to still or slow-flowing water, but it indicates exposure to poor water quality or thermal stress.

  • Do not assume that fish close to the surface are absent or distressed only because of handling. Record water temperature, dissolved oxygen, turbidity and visible surface conditions where safe and permitted.
  • Retain water in refuge pools and avoid sudden dewatering, sediment release, organic pollution and thermal changes.

Sheltering habitat: Known shelter dimensions

The supplied documents do not provide minimum refuge-pool dimensions, vegetation densities, cover percentages or home-range distances. Site-specific refuge assessment should therefore consider persistence of water, aquatic vegetation, substrate, water quality and connection to nearby wetlands or river channels.

Threats: Hydrology and connectivity

The main risks are hydrological change, loss of river to floodplain connectivity, habitat degradation and introduced fish. Clearing and construction can increase these risks through wetland infilling, vegetation removal, sedimentation, pollution and barriers to fish passage.

River regulation has altered seasonal and inter-annual flow regimes and reduced floodplain inundation. Dams, weirs, levees, regulators and culverts can restrict movement, recolonisation and access to billabongs and wetlands.

Cold water releases, changed flow timing and failure to water off-stream habitats can reduce spawning and recruitment. Physical barriers and altered velocities can also isolate small populations.

  • Map all aquatic connections, regulators, culverts, levees, flood runners, billabongs and wetland inlets before works begin.
  • Design temporary and permanent crossings, dewatering arrangements and flow diversions to retain fish passage and avoid isolating occupied wetlands.

Threats: Habitat loss and construction impacts

Removal of riparian vegetation, loss of aquatic plants, siltation, wetland infilling and degradation of billabongs, lagoons and backwaters can remove feeding, refuge and breeding habitat. Construction pollution from domestic, agricultural or industrial sources may also affect the species.

The supplied sources do not identify a species-specific road mortality pattern. Roads and access tracks can nevertheless create indirect risks where they cross waterways, increase sediment delivery or require culverts and temporary water diversions.

  • Keep sediment, concrete washout, fuels, chemicals and other pollutants out of occupied or connected waterways.
  • Avoid removing ribbon weed and other aquatic vegetation from known or potential habitat unless authorised and mitigated.
  • Inspect and manage culverts and temporary crossings so they do not create high velocities, perched outlets or other fish passage barriers.

Threats: Introduced fish, disease and competition

Carp can increase turbidity and damage submerged macrophytes. Redfin perch, gambusia, trout and other salmonids may prey on or compete with flathead galaxias. Gambusia can harass small native fish through fin-nipping and physical displacement and can carry Asian fish tapeworm.

Redfin perch is a principal host of epizootic haematopoietic necrosis virus. Susceptibility of flathead galaxias to this virus is unconfirmed in the supplied advice.

  • Prevent the transfer of alien fish, water, sediment and aquatic equipment between catchments under the relevant hygiene and fisheries procedures.
  • Report suspected flathead galaxias and any unusual fish mortality through the relevant state authority.

Threats: Fire and clearing timing

The supplied documents do not identify fire as a direct species-specific threat. Fire can still affect aquatic habitat indirectly through ash, sediment, erosion, loss of riparian cover and altered runoff after catchment disturbance.

Clearing of aquatic or riparian habitat during spawning and possible upstream movement is more likely to affect the species directly. Site risk remains possible outside those periods where works dewater, isolate or pollute habitat.

  • Use aquatic habitat buffers and erosion controls during vegetation clearing, earthworks and post-fire recovery works near occupied or connected wetlands.
  • Treat any proposed dewatering or channel isolation as a potential impact on fish, regardless of whether fish are seen during a brief inspection.

Survey methodology: 1. Define and inspect aquatic habitat

Flathead galaxias are small, elusive freshwater fish of the southern Murray Darling Basin. Survey design must focus on still or slow flowing wetlands and waterways, including billabongs, lagoons, swamps, dams, backwaters and connected floodplain habitats.

Map all wetlands, billabongs, lagoons, dams, backwaters, lowland streams and floodplain channels that could be affected by the project.

Give priority to habitat with slow or still water, coarse sand or mud, aquatic vegetation, and links to rivers or floodplains.

Inspect connected and nearby retained habitat because barriers can isolate populations and prevent recolonisation.

Typical habitat: Still or slow flowing water bodies, including billabongs, lakes, swamps, rivers, lagoons, dams and backwaters.

Species size: Up to about 146 to 150 mm, but rarely more than 100 mm.

Survey methodology: 2. Targeted fish detection

Use a qualified freshwater fish ecologist to select appropriate, preferably non lethal, sampling methods for the waterbody and its condition.

Consider targeted fish sampling in suitable midwater shoaling habitat, using methods that are lawful and appropriate for threatened native fish.

Use environmental DNA as an additional detection method where abundance is low or conventional capture is difficult, and follow the laboratory and state agency requirements for sample collection and interpretation.

Known survey limitation: The Sustainable Rivers Audit did not detect the species between 2004 and 2010, and only very small numbers have been recorded in later surveys.

Recommended additional method: The conservation advice identifies eDNA as a potential way to detect occupied waterways and document the species range.

  • Treat a non detection cautiously because the species is difficult to sample and has been missed by broad fish surveys.
  • Identify the species by its distinctly flattened head, large mouth and anal fin origin almost directly below the dorsal fin, and distinguish it from obscure and common galaxias.
  • Retain photographs, voucher details where authorised, sampling locations and habitat observations for every detection.

Survey methodology: 3. Seasonal survey timing and conditions

Undertake surveys before disturbance and, where practicable, repeat them during periods when the habitat is connected and suitable for fish movement.

Record water level, flow, temperature, turbidity, aquatic vegetation, dissolved oxygen if measured, recent inundation and barriers to movement.

Give particular attention to spring, when spawning occurs in August and September once water temperatures rise above 10.5 degrees Celsius, and to November and December, when upstream movement has been indicated.

Spawning period: August to September, when water temperatures exceed 10.5 degrees Celsius.

Possible movement period: November to December, when upstream movement has been indicated.

  • Do not treat an absence during a dry, disconnected or poorly accessible period as proof that the species is absent.
  • Coordinate survey timing with environmental watering or natural floodplain inundation where these events affect access to billabongs and wetlands.

Survey methodology: Minimum effort and reporting

  • Use a site specific survey effort approved by the project freshwater fish ecologist and relevant wildlife authority because the supplied documents do not prescribe a standard number of nights, hours, trap nights, transect length or survey area for this species.
  • Survey every suitable waterbody and connected floodplain habitat that may be disturbed, not only the construction footprint.
  • Submit confirmed records, negative survey results and eDNA results to the relevant state wildlife database and the Australian Government species record system where required.
  • Report the location, date, method, effort, waterbody type, water conditions, photographs, identification basis and disposition of any captured fish.
  • Notify the project environmental officer and relevant state threatened species authority immediately if the species is detected or if occupied habitat is identified.

Before habitat disturbance: 1. Avoid and minimise habitat loss

Avoid disturbance to occupied or suitable aquatic habitat wherever practicable. The main project risks are loss of wetland habitat, altered river to floodplain connectivity, barriers, degraded aquatic vegetation, pollution and interactions with introduced fish.

Key habitat feature: Still or slow flowing water with aquatic vegetation and coarse sand or mud substrate.

Connectivity risk: Dams, weirs, levees, culverts and altered flows can restrict movement and recolonisation.

  • Retain billabongs, lagoons, wetlands, dams, backwaters and slow flowing channels within and beside the work area wherever practicable.
  • Retain aquatic vegetation, including ribbon weed and other native submerged or emergent plants associated with the species habitat.
  • Avoid filling, draining, isolating, shading, dewatering or substantially altering waterbodies that could support the species.
  • Maintain water movement between rivers, floodplains and wetlands, and do not create temporary or permanent barriers with access tracks, levees, culverts, cofferdams or spoil.
  • Keep sediment, nutrients, hydrocarbons, concrete washout and other pollutants out of aquatic habitat.

Before habitat disturbance: 2. Approvals and planning

National status: Critically Endangered under the EPBC Act.

Victorian status: Critically Endangered.

  • Confirm the species listing and habitat distribution during the project environmental assessment because it is listed as Critically Endangered under the EPBC Act and as Critically Endangered in Victoria.
  • Obtain advice on whether the action requires an EPBC Act referral or approval before works begin where it may have a significant impact on the species or its habitat.
  • Confirm Victorian permits, approvals, wildlife handling authorities, waterway permits and other state requirements before any survey, capture, relocation, dewatering or habitat disturbance.
  • Prepare a fauna and aquatic habitat management plan that identifies survey results, no go areas, exclusion zones, water quality controls, dewatering procedures, handling authorities, stop work triggers and reporting responsibilities.

Before habitat disturbance: 3. Timing and staging

  • Stage works so that the smallest practicable area is disturbed at one time and suitable retained habitat remains connected throughout the project.
  • Avoid draining, isolating or disturbing occupied habitat during the August to September spawning period where practicable.
  • Avoid blocking likely movement routes during November and December, when upstream movement has been indicated.
  • Schedule dewatering and in water works only after the pre clearance fish survey, approvals and a written fish rescue procedure are in place.

Before habitat disturbance: 4. Prepare and mark the site

  • Complete a pre clearance aquatic habitat inspection and targeted fish survey before machinery enters wetlands, billabongs, lagoons, dams, backwaters or connected channels.
  • Mark no go areas, retained aquatic vegetation, access points, waterway crossings and any habitat occupied by the species.
  • Install exclusion fencing or equivalent controls where they can prevent machinery, sediment, spoil and people entering retained wetland habitat without blocking fish passage.
  • Brief all workers and fauna spotter catchers on the species appearance, habitat, handling limits, stop work triggers and reporting process.

During habitat disturbance: 1. Daily controls

Works near water must be controlled as aquatic fauna operations. A fauna spotter catcher should work under the approved management plan and must not improvise capture, relocation or dewatering procedures.

  • Inspect exclusion fencing, waterway controls, sediment controls, pumps, screens and retained habitat before work starts each day.
  • Keep plant, fuels, chemicals, spoil and concrete washout outside retained aquatic habitat and protect the water from runoff.
  • Prevent sudden dewatering, stranding, high velocity discharge, turbidity pulses and uncontrolled changes in water level.
  • Use screened pump intakes and isolate work areas only under the approved fish rescue and water quality procedure.
  • Stop work during conditions that breach water quality limits, threaten fish passage or cause fish to strand, become trapped or enter machinery areas.

During habitat disturbance: 2. Spotter catcher and machinery interface

  • Keep the fauna spotter catcher in direct communication with the operator and environmental officer during any work near water.
  • Use a defined exclusion distance and slow plant movements around waterbody edges, aquatic vegetation, shallow margins and temporary isolation structures, as specified in the approved management plan.
  • Do not allow machinery to enter a wetland, channel, billabong or lagoon until the spotter catcher confirms that the area has been inspected and the work method is authorised.
  • Keep a safe access route for the spotter catcher and do not require entry into unsafe water, unstable banks, contaminated water or moving plant zones.

During habitat disturbance: 3. Fish and habitat handling

Handling concern: The species is nationally Critically Endangered and has been recorded in very low numbers, so capture and relocation require authorisation and careful handling.

Preferred habitat features: Aquatic vegetation, still or slow flowing water, and coarse sand or mud substrate.

  • If water must be removed or a habitat area isolated, use the approved aquatic fauna rescue team and lawful methods for threatened fish.
  • Do not handle, retain, transport or relocate a flathead galaxias unless the person and procedure are authorised under the applicable state and Commonwealth requirements.
  • If captured, keep the fish in suitable water and minimise handling, air exposure, crowding, temperature change and transport time.
  • Relocate a healthy fish only to nearby suitable retained habitat identified in the approved plan and authorised by the relevant authority.
  • Do not remove aquatic vegetation, mud or coarse substrate from retained habitat unless authorised, and prevent sediment from entering connected water.
  • Treat fish rescue as a specialist aquatic operation; hollow-bearing trees, logs, rocks and burrows are not the primary habitat features for this species, although woody debris and bank structure should not be removed where they support aquatic habitat.

During habitat disturbance: 4. Detection, injury and stop work

  • Stop work immediately if a flathead galaxias is found, if fish are stranded or trapped, or if occupied habitat is exposed or damaged.
  • Protect the location from further disturbance and contact the project environmental officer, fauna spotter catcher and relevant wildlife authority before restarting work.
  • Have an injured fish assessed promptly by an authorised aquatic wildlife professional or veterinarian where available, and follow the authority's direction for treatment or disposal.
  • Record every detection, capture, injury, mortality, relocation, water quality incident and stop work event with date, time, coordinates, method, photographs and people involved.
  • Resume work only after the environmental officer confirms that the approved response has been completed and any additional controls are in place.

After habitat disturbance: 1. Post clearance checks

Post work actions must confirm that fish were not stranded, that aquatic habitat remains connected and that water quality and habitat condition have not been degraded.

  • Inspect all dewatered, isolated, excavated and disturbed aquatic areas for stranded or injured fish before machinery leaves the area.
  • Check downstream and upstream margins, pump sumps, temporary channels, culverts, cofferdams and sediment basins for trapped fauna.
  • Remove temporary barriers only when doing so will not cause a sudden flow, sediment release or fish stranding event.
  • Confirm that retained billabongs, wetlands, lagoons, channels and aquatic vegetation remain connected as required by the approved plan.

After habitat disturbance: 2. Monitoring and reporting

  • Undertake follow up monitoring where habitat was occupied, dewatered, isolated, damaged or restored, using the methods and timing set by the freshwater fish ecologist and relevant authority.
  • Monitor water level, flow, turbidity, aquatic vegetation, bank condition, barriers and evidence of introduced fish at affected and retained sites.
  • Submit records of detections, non detections, mortalities, relocations, incidents and rehabilitation results to the project records system and relevant state wildlife database.
  • Provide any required EPBC Act, Victorian or project approval reports within the specified timeframe.

After habitat disturbance: 3. Maintain controls and offsets

  • Maintain sediment, erosion, water quality and exclusion controls until disturbed ground and aquatic margins are stable and the environmental officer signs them off.
  • Repair failed fencing, crossings, culverts, screens and barriers that could cause stranding or interrupt fish passage.
  • Where residual impacts cannot be avoided, implement approved offsets or compensatory habitat actions that are specific to the species and accepted by the relevant regulator.

Rehabilitation actions: 1. Restore wetland habitat and connectivity

Rehabilitation should restore the slow or still water habitats and connections used by flathead galaxias. It should also reduce the conditions that favour introduced fish, siltation and loss of aquatic vegetation.

Hydrological requirement: The conservation advice identifies floodplain inundation and lateral connectivity as important management priorities.

  • Reinstate billabongs, lagoons, wetlands, dams, backwaters and lowland channels with suitable depth, water permanence and slow flow where these features were disturbed.
  • Restore river to floodplain and wetland connectivity without creating high velocity flows, fish passage barriers or sudden water level changes.
  • Remove or modify temporary barriers and design permanent culverts, crossings and regulators to maintain fish passage where required.
  • Use environmental water or approved watering arrangements to support inundation, spawning, movement and recruitment where this is part of the relevant water management program.

Rehabilitation actions: 2. Reinstate aquatic vegetation and substrates

Planting priority: Native aquatic plants such as Vallisneria species are identified in the conservation advice.

  • Replant or allow recovery of native aquatic vegetation, including suitable Vallisneria species, in occupied or restored billabongs, lagoons, wetlands and dams.
  • Stabilise disturbed banks and control siltation without covering or removing suitable coarse sand, mud or aquatic habitat.
  • Retain suitable woody debris and natural bank structure where they provide cover or help maintain aquatic habitat, while removing only material that creates an approved safety or passage risk.
  • Do not install terrestrial nest boxes or manage hollow-bearing trees as a substitute for aquatic habitat restoration because these are not the primary habitat features identified for this fish.

Rehabilitation actions: 3. Control threats

  • Control carp, redfin perch, gambusia and, where relevant, trout in accordance with approved aquatic pest management programs.
  • Prevent reintroduction and spread of introduced fish between work areas, retained habitat and nearby waterways by cleaning and drying equipment under the relevant biosecurity procedure.
  • Control weeds, sediment sources and polluted runoff that degrade aquatic vegetation and water quality.
  • Manage fire, grazing and bank access only where those pressures affect wetland vegetation, sediment delivery or waterbody persistence, and set the approach with the catchment or land manager.

Rehabilitation actions: 4. Measure rehabilitation success

  • Set success measures for waterbody persistence, fish passage, water quality, aquatic vegetation cover, sediment stability and absence of new barriers before rehabilitation begins.
  • Monitor restored and reference sites for flathead galaxias using targeted fish surveys and, where suitable, eDNA, because the species may be present at low abundance and is difficult to detect.
  • Review rehabilitation after spawning and movement periods, particularly August to September and November to December, and adapt watering, vegetation and pest controls if the habitat is not functioning.
  • Report rehabilitation outcomes, survey effort, detections and management changes to the project environmental officer and relevant wildlife authorities.

Sources