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Great Lake Paragalaxias (Paragalaxias eleotroides)

The Great Lake Paragalaxias (Paragalaxias eleotroides) is a small, endemic Tasmanian freshwater fish found in yingina, or Great Lake, and associated lagoons on the Central Plateau. It is listed as Vulnerable under the EPBC Act and Tasmanian legislation, so works affecting lake margins, rocky shallows, algal beds, water quality or lake levels may affect habitat used for feeding, shelter and breeding.

Conservation status

Commonwealth, EPBC Act 1999: Vulnerable.

Tasmania, Threatened Species Protection Act 1995: Vulnerable.

Breeding season

The species is non-diadromous and remains in freshwater. The seasonal pattern below is based on the reported spring breeding season and the need to protect shallow lake habitat while eggs and young may be present.

Months are January to December. The breeding and risk periods are based on the documented spring breeding season; the exact timing of spawning and early development is not known.

  • Breeding: Breeding is reported in spring. September to November is used as the typical peak period.
  • Eggs and early young: Eggs are expected after spring spawning, but the incubation period and timing of early life stages are not reported.
  • Juvenile growth: The species matures at one year. No more detailed monthly pattern for juveniles is provided.
  • Highest clearing risk: Risk is highest during spring breeding and the following period when eggs and early young may be present. Lake-margin disturbance and hydrology changes should also be avoided outside this period where they could remove or alter habitat.

Identification

This is a small, stout, scaleless galaxiid associated with cold Central Plateau lakes and lagoons. Identification should be confirmed by an experienced freshwater fish ecologist, particularly where it occurs with the similar Shannon paragalaxias and other galaxiids.

The Great Lake paragalaxias grows to approximately 60 mm. It has a steeply profiled snout that curves down to a mouth set low on the head. The dorsal fin is long and begins above the pelvic fins, while the tail is emarginate or only slightly forked.

The back is light brownish gold with irregular brown speckled patches. The markings become diffuse down the sides. The belly is pale yellow to white, and the fins are amber with distinct black specks along the fin rays.

Maximum reported length: Approximately 60 mm

Body form: Small and stout

Tail: Emarginate or only very slightly forked

Identification: Distinguishing features

The species is largely benthic, unlike the more mid-water Shannon paragalaxias. It is associated with rocky shallows and algal beds, although the full depth range is unresolved and older observations suggested that it may also occur deeper in Great Lake.

The species shares its known localities with Shannon paragalaxias. Field identification should therefore use the combination of body shape, low-set mouth, long dorsal fin, fin markings, habitat and, where needed, specialist examination rather than locality alone.

Identification: Field signs and handling

There are no reported tracks, scats, calls, nests or other terrestrial field signs. Presence is normally established by direct capture during standardised fish surveys, including fine-mesh fyke nets in lakes and electrofishing or scoop-net methods where suitable.

Any capture during project work should be treated as a threatened-fish record. Avoid unnecessary handling, return native fish promptly to the capture water, and use appropriately permitted methods and equipment.

Distribution: Range and strongholds

The Great Lake paragalaxias is endemic to Tasmania and has a highly restricted range on the Central Plateau. Available sources do not provide a reliable total population estimate.

The species is known from yingina, or Great Lake, Shannon Lagoon and Penstock Lagoon in central Tasmania. Recent monitoring describes the broader connected system as including the Shannon River.

Great Lake is the principal known stronghold. The species is relatively abundant there, but is uncommon in Shannon Lagoon and rare in Penstock Lagoon, where rocky habitat suitable for feeding and spawning is limited.

State range: Tasmania only

Bioregional setting: Central Plateau of Tasmania

Known waterbodies: Great Lake, Shannon Lagoon and Penstock Lagoon; associated Shannon River system

Distribution: Population information

The species has a limited distribution and a small number of fragmented localities. Its abundance, habitat preferences and habitat distribution have been monitored through fyke-net surveys and other studies, but the supplied documents do not give a whole-population estimate.

In 2024, monitoring at Shannon Lagoon recorded one Great Lake paragalaxias and monitoring at Penstock Lagoon recorded none. The 2024 report states that the species is relatively abundant in Great Lake but uncommon in the two lagoons.

EPBC Act status: Vulnerable

Tasmanian status: Vulnerable

Shannon Lagoon result, April 2024: 1 fish captured in 16 fine-mesh fyke nets set overnight

Penstock Lagoon result, April 2024: 0 fish captured in 16 fine-mesh fyke nets set overnight

Habitat: Habitat types

The species occupies freshwater lakes and lagoons on the Tasmanian Central Plateau. Habitat quality depends on shallow nearshore structure, algal beds, water quality and suitable lake levels.

The Great Lake paragalaxias occurs in rocky shallows and algal beds around lake shores. Fish shelter beneath rocks and vegetation and are largely benthic.

Great Lake provides more suitable habitat than Shannon Lagoon and Penstock Lagoon. The latter two lagoons have less rocky habitat and limited feeding and spawning areas.

Habitat: Physical features and hydrology

Important features include shallow rocky margins, submerged vegetation and algal beds. The spawning site has not been located, so all suitable shallow habitat should be treated cautiously during works.

Lake-level changes can expose, inundate or otherwise alter shallow rocky and algal habitat. Water-level management in Great Lake and the associated lagoons is therefore relevant to habitat availability and water quality.

Depth information: The species was not found in some surveys of algal and rocky habitat from 1 to 7 m depth, although older observations suggested it may occur deeper.

Elevation or climate limit: No specific elevation or climatic limit is provided in the supplied documents.

Habitat: Development-site implications

Assess the full area that may be affected, including lake margins, inflow areas, downstream waters and locations affected indirectly by altered drainage, sediment or water levels.

Avoid activities that reduce water quality, damage rocky shallows or algal beds, remove submerged cover, or change lake-level conditions without species-specific advice and approval.

Foraging habitat: Diet

The Great Lake paragalaxias feeds mainly on the lake bed and among nearshore structure. Its feeding habitat is closely associated with rocky shallows, algal beds and submerged vegetation.

The diet consists mainly of benthic aquatic insect larvae. Planktonic crustaceans and some algae are also eaten.

Main prey: Benthic aquatic insect larvae

Additional food: Planktonic crustaceans and some algae

Foraging habitat: Foraging areas and method

The species is largely benthic and forages around rocky lake margins and algal beds. It shelters beneath rocks and vegetation, so disturbance or removal of these features can reduce both feeding and refuge habitat.

No foraging-range distance or home-range estimate is provided. The species is non-diadromous and completes its life cycle in freshwater.

Foraging position: Mainly on or near the lake bed

Foraging habitat: Rocky shallows, algal beds and areas with submerged vegetation

Movement between habitats: No quantified foraging range is available

Breeding habitat: Breeding biology

Breeding occurs in freshwater, but the exact spawning site has not been identified. Spring breeding and the species' association with shallow rocky and vegetated margins indicate that these habitats require protection during works.

Breeding takes place in spring. Females lay up to 150 eggs, each approximately 2 mm in diameter. The spawning site has not been found.

The species matures at one year of age. No reliable information on lifespan, incubation period or the duration of parental care is provided in the supplied documents.

Breeding season: Spring

Eggs per female: Up to 150

Egg diameter: Approximately 2 mm

Age at maturity: One year

Incubation period: Not reported

Lifespan: Not reported

Breeding habitat: Breeding habitat

The precise spawning habitat is unknown. Rocky shallows, algal beds and submerged vegetation are associated with the species and should be considered potential breeding habitat, particularly in Great Lake and connected lagoons.

Avoid dewatering, sediment deposition, physical disturbance and rapid water-level changes in these habitats during spring. Survey design should account for the possibility that spawning occurs outside the shallow areas sampled previously.

Sheltering habitat: Known refuges

Shelter is provided by physical cover in shallow freshwater habitats. The species is reported to shelter beneath rocks and vegetation and to use algal beds.

The species shelters beneath rocks and vegetation around lake shores. Rocky shallows and algal beds provide cover as well as feeding habitat.

No den, burrow, hollow, nest, roost or refuge-size measurement is reported. The species may occur at greater depth than has been detected by previous surveys, so deeper habitat should not be excluded without evidence.

Shelter features: Rocks, submerged vegetation and algal beds

Known refuge size: Not reported

Possible deeper habitat: Older observations suggested occurrence at depth, but the depth range remains unresolved

Sheltering habitat: Protection during works

Keep machinery, sediment, fuels and concrete washout away from connected waters and lake margins. Prevent fish entrapment in temporary excavations, sumps and isolated pools.

Do not move water, aquatic plants, fish or equipment between catchments or waterbodies without appropriate biosecurity controls. Introduced fish are a recognised threat to this species and its associated galaxiid habitats.

Threats: Introduced fish

The main risks are introduced fish, deterioration or loss of shallow lake habitat, water-level changes and declining water quality. These risks are serious because the species has a restricted range and fragmented localities.

Introduced fish species can prey on Great Lake paragalaxias, compete for resources and reduce access to open-water habitat. The recovery plan identifies introduced fish as a threat and recommends preventing pest-fish introductions and attempting eradication if they occur.

Project vehicles, boats, nets and water transfers can spread aquatic pests between catchments. Use site-specific aquatic hygiene and biosecurity procedures.

Threats: Habitat loss and hydrology

Changes in lake levels can reduce or alter shallow rocky and algal habitat. Habitat deterioration, changes in water quality and reduced habitat availability are recognised risks.

Works that alter inflows, outflows, drainage, sediment delivery, water levels or shoreline structure may affect habitat directly or indirectly. Include downstream and connected-lagoon effects in the impact assessment.

Threats: Clearing, fragmentation and construction disturbance

Direct clearing of riparian or shoreline vegetation can remove cover and increase sediment and nutrient inputs. Shoreline excavation, access tracks, bank works and temporary laydown areas can damage rocky shallows and algal beds.

Although the species is aquatic, terrestrial works within its catchment can affect it through erosion, altered runoff, pollution and changed hydrology. Maintain undisturbed drainage and prevent sediment from entering connected waters.

Threats: Other pressures

The supplied documents do not identify a species-specific disease, road mortality or fire regime. These pressures should still be considered where a project can introduce pollutants, isolate waterbodies, alter catchment runoff or create barriers to water movement.

The species is listed as Vulnerable under both the EPBC Act and Tasmanian legislation because of its restricted distribution, fragmented localities and risk of future decline from habitat deterioration and introduced fish.

Survey methodology: 1. Confirm habitat and survey extent

Great Lake paragalaxias is a small, benthic freshwater fish found in central Tasmania. Surveys must cover the full area that may be affected, including downstream waters, lake margins, connected lagoons and changes to water levels or water quality.

Map the project footprint and all areas that could be affected directly or indirectly, including downstream reaches, lake margins, wetlands, connecting channels and areas affected by altered water levels.

Treat rocky shallows, nearshore algal beds and other shallow lake-margin habitat as target habitat. The species has been recorded from yingina, or Great Lake, Shannon Lagoon and Penstock Lagoon, with Great Lake the principal known locality.

Check current records and predictive mapping with Australian Government, Tasmanian Government and Inland Fisheries Service sources before finalising the survey design.

Known range: Great Lake, Shannon Lagoon and Penstock Lagoon on the Tasmanian Central Plateau

Adult size: Up to approximately 60 mm

Habitat: Rocky shallows and algal beds around lake shores; the species is largely benthic

Survey methodology: 2. Fine-mesh fyke-net survey

Use fine, soft-mesh fyke nets in lakes and lagoons where safe access and approval are available.

Set nets overnight along representative shoreline habitats, including rocky shallows, algal beds and any other habitat likely to be affected.

Fit nets with screens to prevent access by platypus and large trout, and keep cod ends out of the water or buoyed to reduce drowning risk.

Record the number of nets, set locations, soak period, habitat type, water level, weather and all captures so results can be expressed as catch per unit effort.

Documented monitoring effort: The 2023 to 2024 IFS survey used 16 fine-mesh fyke nets overnight along the shoreline at each of Penstock Lagoon and Shannon Lagoon.

Recent detection result: In April 2024, one Great Lake paragalaxias was captured at Shannon Lagoon and none at Penstock Lagoon.

Survey methodology: 3. Electrofishing and scoop-net survey

Use backpack electrofishing for suitable shallow shoreline or connecting-stream habitat, operated by trained personnel under the applicable code of practice and permit conditions.

Use a flat dip net to slide fish into a bucket, and use the lowest effective electrofishing setting to reduce injury.

Use small scoop nets where electrofishing is unsuitable or where a lower-impact method is preferred.

Allow at least 30 minutes of backpack electrofishing for each stream or lake-shore site, with additional effort where habitat is extensive, access is difficult or detection is poor.

Do not assume that a negative shoreline survey excludes the species. It may occur at greater depth, and the spawning site is not known.

General galaxiid settings reported in the guideline: 60 Hz and 2 or 4 mS, with voltage generally between 200 and 700 V, adjusted to conductivity and used as low as practicable

Detection note: Some galaxiids are more active near shore at night, while daytime fish may be in depths where electrofishing is not feasible.

Survey methodology: 4. Timing and repeat surveys

Survey in conditions that allow safe access and effective detection, and document turbidity, water level, flow, temperature and other conditions that may affect capture rates.

Consider night sampling where quantitative assessment is required, because many galaxiids are more active at night and closer to shore. Use daylight where identification and safe release are the priority.

Plan repeat or depth-targeted surveys where one survey cannot adequately cover deep water, variable lake levels, poor weather or the full range of affected habitat.

Consider spring and summer activity when planning targeted work because Great Lake paragalaxias breeds in spring and some paragalaxias may breed in summer, although the precise spawning site is unknown.

Survey methodology: Minimum effort and reporting

  • Survey every suitable rocky shallow, algal bed, shoreline section and connected waterbody that may be disturbed, including downstream areas affected by the project.
  • Use at least 30 minutes of backpack electrofishing for each suitable stream or lake-shore site, or use overnight fine-mesh fyke nets in lakes and lagoons where permitted and safe.
  • Record effort, coordinates, habitat, water conditions, equipment settings, captures, photographs and release or relocation details.
  • Have all electrofishing, netting, collection, handling and relocation undertaken by appropriately trained and authorised personnel under the relevant Tasmanian permit and animal ethics requirements.
  • Submit confirmed records, including negative survey results where required by the project approval, to the Tasmanian Natural Values Atlas or other relevant Tasmanian wildlife database and provide records to the Inland Fisheries Service.
  • Retain voucher photographs and seek expert confirmation for uncertain identifications because the species is small and may occur with other galaxiids.

Before habitat disturbance: Avoid and minimise habitat loss

Plan the project around the species' very restricted range and dependence on shallow freshwater habitat. Avoid disturbance to rocky shallows, algal beds, water quality and lake-level conditions wherever practicable.

  • Redesign the works to retain rocky lake margins, shallow-water areas, algal beds, connecting channels and riparian vegetation associated with occupied or suitable habitat.
  • Keep machinery, spoil, fuels, concrete washout and sediment out of the water and away from drainage lines that flow to Great Lake, Shannon Lagoon or Penstock Lagoon.
  • Maintain connectivity between retained habitat patches and connected waterbodies unless an approved design requires otherwise.
  • Do not set a generic buffer without a site assessment. Define project-specific no-go areas and setbacks with the aquatic ecologist, considering the species' unknown spawning habitat and possible use of deeper water.
  • Avoid changes to water level, drawdown, flow, turbidity or water quality. The recovery plan identifies habitat deterioration, introduced fish and water-level management as conservation concerns.

Before habitat disturbance: Approvals and work planning

Listings: EPBC Act Vulnerable and Tasmanian Vulnerable

  • Check whether the action may significantly affect Great Lake paragalaxias habitat or individuals and refer the action under the EPBC Act if required, because the species is nationally listed as Vulnerable.
  • Obtain Tasmanian permits for collecting, handling, electrofishing, fyke netting, relocation or other interference with freshwater fauna before work starts.
  • Consult the Inland Fisheries Service and the relevant Tasmanian threatened-species authority about current records, survey design, water-level controls and pest-fish safeguards.
  • Prepare a fauna and aquatic habitat management plan that sets out survey limits, exclusion areas, water-quality controls, authorised handlers, stop-work triggers, relocation procedures and reporting.
  • Stage works to keep suitable habitat connected and to limit the duration of dewatering, isolation, shoreline access and in-water activity.

Before habitat disturbance: Pre-clearance and site preparation

  • Complete the approved pre-clearance aquatic survey before machinery enters the work area and repeat it if water levels, access or the work footprint changes materially.
  • Mark no-go aquatic habitat, retained shoreline, exclusion zones, access routes and any approved relocation or holding areas on plans and on the ground.
  • Install sediment, erosion and spill controls before disturbance, and inspect them after rainfall and during daily works.
  • Use exclusion fencing or other physical controls where they can prevent machinery and people entering retained shoreline habitat without blocking fish movement or causing erosion.
  • Brief all operators and spotter catchers on the species' appearance, likely habitat, handling limits, stop-work triggers and incident contacts.

During habitat disturbance: Daily controls and machinery interface

Keep works outside retained aquatic habitat and maintain continuous supervision while machinery operates near water. Great Lake paragalaxias must only be handled by authorised personnel using the approved method.

  • Hold a daily pre-start briefing covering water levels, weather, exclusion zones, access routes, approved work limits and any previous fauna observations.
  • Inspect sediment barriers, spill kits, exclusion fencing, pumps, screens and escape routes before work begins.
  • Keep the fauna spotter catcher between the active machinery and the retained aquatic habitat where safe, and require machinery to stop before the spotter catcher enters the exclusion zone or signals a fauna risk.
  • Use a spotter catcher for any approved fish salvage, dewatering or isolation work, but do not allow the spotter catcher to enter unsafe water, operate machinery or undertake electrofishing without the required authority and training.
  • Stop work immediately for a spill, uncontrolled sediment discharge, fish stranding, unexpected water-level change, pest-fish detection or any activity outside the approved footprint.

During habitat disturbance: Aquatic habitat and fauna handling

  • Avoid disturbing rocky shallows, algal beds and other shallow-margin habitat unless the disturbance is approved and cannot be avoided.
  • Do not move rocks, woody material or aquatic vegetation unnecessarily, and do not leave isolated pools, stranded fish or blocked connections during dewatering or temporary isolation.
  • If a Great Lake paragalaxias is found, stop the activity that may affect it and keep the fish in clean, aerated water handled by the authorised aquatic fauna team.
  • Release the fish into nearby retained habitat identified in the approved plan, unless the permit or aquatic specialist directs another outcome.
  • Do not relocate fish between catchments or waterbodies without written approval and a biosecurity assessment, because accidental transfer of introduced fish is a recognised conservation risk.
  • Send injured fish to an authorised aquatic wildlife carer, veterinarian or government contact, following the permit and animal-welfare procedure.

During habitat disturbance: Records and incident response

  • Record the date, time, location, waterbody, habitat, species, number of individuals, size where measured, condition, action taken, destination and names of authorised personnel for every encounter.
  • Photograph the fish and habitat where this can be done without delaying safe release or increasing handling time.
  • Record water quality observations, turbidity, water levels, dewatering volumes, sediment events, pest fish and any breach of exclusion controls.
  • Notify the site environmental officer, project manager, aquatic ecologist and relevant approval authority of a confirmed capture, mortality, injury, pest-fish detection or unplanned impact.
  • Maintain a daily fauna register and map all observations and incidents so the information can be supplied to the Tasmanian Natural Values Atlas, Inland Fisheries Service and approval agencies.

After habitat disturbance: Immediate post-clearance checks

Post-work checks must confirm that fish were not stranded or injured and that retained habitat remains connected and suitable. Continue controls until the site is stable and approved rehabilitation is complete.

  • Inspect the work area, isolated pools, drains, bypass channels, screens and downstream margins for stranded, injured or dead fish as soon as each work stage is completed.
  • Remove temporary barriers, pumps, pipes and access structures only after the aquatic ecologist confirms that fish passage and safe water depth have been restored.
  • Check rocky shallows, algal beds, shoreline cover, water quality and sediment controls against the approved pre-work condition and rehabilitation plan.
  • Keep exclusion fencing, sediment controls and spill response equipment in place until exposed soil, banks and access tracks are stable.

After habitat disturbance: Monitoring and reporting

  • Undertake follow-up fyke-net, scoop-net or electrofishing monitoring where the approval, risk assessment or aquatic ecologist identifies a risk of residual impact.
  • Repeat monitoring where the first post-work survey is affected by poor water level, turbidity, access or other conditions that reduce detection.
  • Compare post-work catch rates, habitat condition, water levels and water quality with the pre-work survey and relevant long-term monitoring data.
  • Report captures, mortalities, injuries, pest fish, water-quality incidents, rehabilitation results and any corrective action to the approval authorities and relevant Tasmanian wildlife database.
  • Review the work method before the next stage if monitoring shows habitat loss, reduced connectivity, declining detection or unexpected fish impacts.

After habitat disturbance: Offsets and residual impacts

  • Determine whether an offset is required under the EPBC Act, Tasmanian approvals or project conditions after avoidance, minimisation and rehabilitation measures have been applied.
  • Do not treat an offset as a substitute for retaining occupied rocky shallows, algal beds, water quality and water-level conditions at the project site.
  • Document the area and condition of habitat lost, retained, restored or protected, and link any approved offset to the species' known central Tasmanian habitat and threatening processes.

Rehabilitation actions: Restore aquatic habitat

Rehabilitation should restore shallow freshwater habitat and the water regime used by Great Lake paragalaxias. The species' spawning site and full depth distribution are not known, so rehabilitation must be guided by site data and follow-up monitoring.

  • Regrade disturbed margins to provide stable shallow-water habitat connected to retained shoreline areas.
  • Reinstate or retain clean rocky substrate and suitable algal-bed habitat where these features formed part of the pre-work site.
  • Prevent sediment, nutrient, chemical and weed inputs that could reduce water quality or smother rocky shallows and algal beds.
  • Restore natural drainage and fish passage, and remove temporary barriers when the site is stable and safe.
  • Manage lake-level and drawdown effects through the approved water-management arrangements, because changes in water level can reduce habitat availability.

Rehabilitation actions: Control introduced fish and other threats

  • Implement a biosecurity plan that prevents the transfer of pest fish, water, equipment and contaminated material between catchments and waterbodies.
  • Inspect and disinfect nets, electrofishing equipment, pumps, footwear and vehicles before moving between sites, in accordance with the approved Tasmanian procedure.
  • Report any redfin or other non-indigenous fish immediately to the Inland Fisheries Service and follow the approved containment or eradication response.
  • Manage recreational or commercial fishery interactions and public access where required to reduce the risk of illegal fish introductions.
  • Control erosion, weeds and other catchment activities that could reduce water quality or habitat availability.

Rehabilitation actions: Monitor rehabilitation success

Documented recovery needs: The recovery plan identifies regular population monitoring, research into habitat and spawning requirements, water-level management and genetic information as management needs.

  • Monitor restored shoreline habitat, rocky substrate, algal beds, water quality, water levels, fish passage and introduced-fish presence at intervals set by the approval and aquatic ecologist.
  • Use consistent fine-mesh fyke-net, scoop-net or electrofishing methods at fixed sites so results can be compared through time.
  • Measure Great Lake paragalaxias detections and catch per unit effort, recruitment where fish can be safely measured, habitat condition and any signs of spawning habitat use.
  • Include deeper-water sampling in the monitoring design where the project could affect deeper habitat, because the species may occur at depth and its spawning site remains unknown.
  • Treat rehabilitation as successful only when approved habitat features are stable, water quality and connectivity are maintained, pest fish are absent or controlled, and monitoring shows continued presence or recovery of Great Lake paragalaxias.

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