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Honey Blue Eye (Pseudomugil mellis)

The Honey Blue-eye is a small freshwater fish endemic to coastal south-east Queensland, occurring in wallum lakes, lagoons, swamps and small streams. Development can affect the species through clearing, altered water tables, sedimentation, pollution, habitat fragmentation and competition from introduced Mosquito Fish.

Conservation status

Commonwealth, EPBC Act 1999: Endangered.

Queensland, Nature Conservation Act 1992: Endangered.

Breeding season

The available survey information indicates that Honey Blue-eyes may be present through most of the year. Abundances were higher from October to December, but the breeding period and timing of dependent young are not specified.

Survey guidelines report that traps are most effective within two hours after dawn and before dusk, with fish removed 15 to 45 minutes after setting. Unbaited traps were used within an hour after dawn and dusk in the cited study. Survey methods must be selected and implemented under the relevant approvals.

  • Breeding: Breeding is documented in submerged vegetation, but no confirmed months are given. All months are marked as possible rather than peak.
  • Young: The cited documents do not give a season for eggs, larvae or dependent young. Potential presence should therefore be assumed throughout the year in occupied breeding habitat.
  • Survey presence and abundance: Honey Blue-eyes were collected in all months except July in the Noosa River, with higher abundances from October to December.
  • Movement or dispersal: No seasonal migration or dispersal period is reported. Most populations are isolated, so local movement should not be assumed to compensate for habitat loss.
  • Highest clearing risk: No breeding season is established. Clearing and hydrological disturbance may affect fish, eggs or aquatic vegetation in any month, so avoid works in occupied or potential habitat year round unless impacts are controlled and approvals are in place.

Identification

The Honey Blue-eye is a very small, slender freshwater fish associated with shallow vegetated margins. Identification requires care because it can occur with the similar Pacific Blue-eye and can be confused with juvenile sand mullet.

Breeding males are honey to copper coloured, with a dusky head, a single dark midlateral line, blue eyes and iridescent blue cheeks.

Females are plain amber with clear fins. The species is generally only about 3.5 to 3.8 cm long.

Male appearance: Honey to copper body, dusky head, dark midlateral line, blue eyes and iridescent blue cheeks.

Female appearance: Plain amber body with clear fins.

Maximum reported size: About 3.8 cm; 3.5 cm standard length is also reported.

Weight: Not reported in the cited documents.

Identification: Similar species

The Pacific Blue-eye, Pseudomugil signifer, is a close relative that occurs in some of the same localities. Juvenile sand mullet are another possible source of confusion, but they are more slender bodied and belong to the mullet family.

Visual censuses are not always reliable. Use an experienced freshwater fish ecologist where the species may occur, and retain clear side-on photographs or other approved identification material where required.

  • Check the small size, blue eyes, dark midlateral line and blue cheek iridescence, especially in breeding males.
  • Do not rely on a brief visual observation alone where Pacific Blue-eyes or juvenile sand mullet are present.
  • Use small seines, hand-held dip nets or suitable traps only under the relevant approvals and animal ethics requirements.

Identification: Field signs

No tracks, scats, calls, nests, burrows, sloughs or eyeshine are produced by this species. The practical field indication is the presence of very small blue-eyed fish among emergent or submerged aquatic plants at the margins of suitable lakes, streams, swamps and lagoons.

Eggs are demersal, adhesive and attached to submerged plants, but they are small and are not a reliable sign for routine construction-site inspections.

  • Inspect shallow, sheltered margins with sedges, reeds, water lilies or other aquatic macrophytes.
  • Treat fish seen in suitable wallum waterbodies as requiring confirmation rather than dismissing them because they are difficult to identify visually.

Distribution: National range

The Honey Blue-eye is endemic to a restricted section of coastal Queensland. Its distribution is patchy, and many populations are isolated from one another.

The species is known only from Queensland. Its range extends from around Brisbane northwards along the coast to the Bundaberg area, including Fraser Island.

It occurs in freshwater lagoons, small lakes and small streams between Brisbane and Fraser Island, with additional records in coastal creeks, swamps and dune lakes.

States and territories: Queensland only.

Approximate range: Brisbane area to Bundaberg area, including Fraser Island.

Natural Resource Management regions: Burnett-Mary and South East Queensland.

Distribution: Strongholds and subpopulations

The species has been reported from about 18 locations on the mainland and Fraser Island. Most populations are described as totally isolated from one another.

Relatively abundant populations were reported in the Noosa River and Fraser Island localities. Records also include creeks near Caloundra, Little Yabba Creek west of Maroochydore, Noosa River, Wide Bay creeks and several Fraser Island waterbodies.

Reported locations: About 18 mainland and Fraser Island locations.

Population structure: Most populations are isolated from one another.

Population size: No total population estimate is provided in the cited documents.

Trend: No quantified population trend is provided. Mainland populations are described as endangered in the FishBase summary.

  • Known protected-area locations include Mellum Creek Scientific Reserve, Cooloola National Park and Fraser Island National Park.
  • Mainland and island populations should be treated as potentially separate management units because of their isolation.

Distribution: Project screening

For a project assessment, map all lakes, lagoons, wetlands, small streams and downstream receiving waters within the project area and any area that may be indirectly affected. Compare those features with current Queensland and Australian Government species records.

A lack of a local record does not exclude the species. The conservation advice identifies survey work in suitable and potential habitat as a priority.

  • Include downstream areas that could receive altered flows, sediment or pollutants.
  • Check both permanent and seasonal waterbodies where suitable aquatic vegetation is present.
  • Use current government databases and local records before finalising the survey area.

Habitat: Waterbodies and vegetation

Honey Blue-eyes occupy lowland coastal freshwater habitats in wallum country. They favour slightly acidic, low-conductivity water with limited flow and dense aquatic vegetation along the margins.

Habitat includes tannin-stained lakes and streams, clear or stained creeks, coastal dune lakes, lagoons, swamps and small streams. Water may have a sandy or muddy bottom.

The fish usually occurs where there is little or no flow and where emergent or submerged sedges and other aquatic macrophytes provide cover along the margins.

Typical pH: Slightly acidic; FishBase reports a range of pH 4.5 to 5.8 for described habitat, while its broader species data list pH 6.0 to 8.0.

Flow: Usually little or no flow, although the species also occurs in running waters.

Substrate: Sand or mud.

Water colour: Clear to darkly tannin stained.

  • Retain aquatic and emergent vegetation at the margins of suitable waterbodies.
  • Protect connections between the waterbody, its margins and any upstream or downstream drainage features.
  • Assess both clear and tea-coloured water because water colour alone does not exclude the species.

Habitat: Climate and elevation

The cited documents place the species in lowland coastal south-east Queensland and do not provide a confirmed elevation limit.

FishBase gives a distribution around 26 to 27 degrees south and a reported tropical temperature range of 24 to 28 degrees Celsius, but these figures should not be used as a substitute for local habitat assessment.

Elevation limit: Not reported in the cited documents.

Reported geographic latitude: Approximately 26 to 27 degrees south in FishBase.

  • Assess the physical and chemical condition of each waterbody rather than relying on elevation alone.
  • Consider seasonal water-level changes, groundwater connections and drainage alterations when defining potential habitat.

Foraging habitat: Feeding areas

The cited documents do not provide a species-specific diet or measured foraging range. They show that Honey Blue-eyes use shallow, vegetated margins in still or slow-flowing freshwater habitats.

The species is associated with grassy banks, reeds, water lilies and other emergent or submerged aquatic plants. These shallow margins are likely to provide the main feeding area as well as shelter.

The documents do not identify particular food plants, prey species, feeding depth or home-range size.

Diet: Not specified in the cited documents.

Known foraging setting: Shallow margins of small streams, lakes, lagoons and swamps, often among aquatic macrophytes.

Foraging range: Not reported.

  • Protect vegetated shallow margins, including areas outside the ordinary open-water channel.
  • Avoid sediment, pollution and vegetation loss that could reduce water quality or the invertebrate resources associated with aquatic plants.
  • Do not infer that an unvegetated section is unoccupied simply because fish are not visible during a brief inspection.

Breeding habitat: Breeding features

Honey Blue-eyes spawn within a male territory in submerged vegetation. The eggs attach to plants, so removal or disturbance of aquatic macrophytes can directly affect breeding habitat.

Breeding occurs in submerged vegetation within a male's territory. Eggs are demersal and adhesive, and are attached to plants.

The cited documents do not provide a confirmed breeding season, clutch size, incubation period, age at maturity or lifespan. Survey records show fish in most months and higher abundances from October to December, but abundance is not the same as a breeding record.

Breeding site: Submerged vegetation within a male territory.

Eggs: Demersal, adhesive and attached to plants.

Breeding season: Not specified in the cited documents.

Clutch size: Not reported.

Incubation period: Not reported.

Age at maturity: Not reported.

Lifespan: Not reported.

  • Retain submerged and emergent aquatic vegetation in suitable shallow margins.
  • Avoid works that cause rapid water-level changes, sedimentation, pollution or loss of low-flow refuge.
  • Obtain specialist advice before disturbing vegetation in occupied or potential habitat.

Sheltering habitat: Cover and refuge

Shelter is provided by dense aquatic vegetation along shallow, low-flow margins. No separate nest, burrow, hollow, den or roost structure is used.

The species usually occurs where emergent and submerged sedges and other aquatic macrophytes provide shelter. Reeds, water lilies and grassy banks are also associated with records.

The documents do not provide a minimum vegetation patch size, refuge depth, home range or specific shelter dimensions.

Primary refuge: Dense emergent and submerged aquatic vegetation.

Associated cover: Sedges, reeds, water lilies and grassy banks.

Refuge dimensions: Not reported.

  • Retain dense marginal vegetation and avoid clearing access tracks through shallow vegetated water margins.
  • Prevent smothering of aquatic cover by sediment and avoid chemical use that could adversely affect the fish or its habitat.
  • Treat isolated ponds and stream margins as potential refuge habitat even when they are not connected by obvious surface flow.

Threats: Clearing and construction

The main project risks are loss and degradation of wallum waterways, changes to hydrology and water quality, and the spread or presence of introduced Mosquito Fish. Small, isolated populations may be especially sensitive to local impacts.

Habitat clearing and degradation associated with residential, forestry and agricultural development are identified threats. Project activities can also affect habitat indirectly through altered drainage, increased runoff, sedimentation and pollution.

Because most populations are isolated, loss of one occupied waterbody or its vegetated margins may not be readily offset by recolonisation from nearby sites.

  • Avoid clearing lakes, lagoons, swamps, small streams and vegetated margins in the known range.
  • Map direct and indirect impact pathways, including downstream receiving waters and groundwater or water-table effects.
  • Use sediment, erosion, runoff and pollution controls that maintain the existing water quality and flow regime.
  • Prevent construction access and public access from damaging known sites.

Threats: Hydrology and water quality

Changes to water-table levels, runoff, sedimentation, pollution and other hydrological processes can degrade habitat. The species uses low-pH, low-conductivity waters, so changes to catchment inputs may alter suitable conditions.

Weed-control chemicals and other treatments must not have a significant adverse effect on Honey Blue-eyes or their aquatic habitat.

  • Maintain the water levels, drainage connections and low-flow conditions characteristic of the site.
  • Control sediment and contaminated runoff before it enters potential habitat.
  • Assess whether dewatering, excavation, culverts, crossings or altered drainage will affect water tables or downstream wetlands.
  • Select weed-control methods that protect fish, eggs and aquatic plants.

Threats: Introduced fish and collection

Competition from introduced Mosquito Fish, Gambusia holbrooki, is a main identified threat. The conservation advice recommends regional control and eradication planning.

Collection for aquariums is also identified as a threat. Fish are protected, so capture, handling, retention and translocation require appropriate approval.

  • Do not release aquarium fish or use water, equipment or stock that could spread Mosquito Fish between catchments.
  • Clean and dry fish-survey equipment between waterbodies in accordance with approved hygiene procedures.
  • Use only authorised survey and relocation methods.

Threats: Fire, roads and disease

The cited documents do not identify fire, roads or disease as species-specific threats, and they do not provide a disease list or fire response threshold.

These pressures should still be considered where they can alter water quality, runoff, aquatic vegetation, access or the spread of introduced fish. Site-specific assessment is required.

  • Assess whether firebreaks, roads, crossings or drainage works could increase sediment, runoff or isolation of waterbodies.
  • Prevent dirty water and contaminated equipment from entering potential habitat.
  • Seek species-specific advice if disease, fish translocation or emergency water-quality works are proposed.

Survey methodology: 1. Map and assess habitat

Survey Honey Blue-eye in suitable freshwater habitat before works begin. Focus on small streams, lagoons, swamps and dune lakes with low pH, low conductivity, clear to darkly stained water and dense aquatic macrophytes.

Map the full project area and any downstream or indirectly affected waters before selecting survey sites.

Inspect small streams, lagoons, lakes, swamps and coastal wallum waters with sandy or muddy bottoms, little flow and emergent or submerged sedges, reeds or other aquatic plants.

Record water condition, aquatic vegetation, flow, bank access and connections between suitable waterbodies, because populations are patchy and often isolated.

Survey methodology: 2. Set unbaited traps

Use commercially available bait traps with approximately 3 mm mesh, an open inverted funnel at each end and a box approximately 250 by 250 by 450 mm.

Set traps within two hours after dawn and before dusk, or within one hour after dawn and within one hour after dusk where following the Arthington and Marshall method.

Clear traps 15 to 45 minutes after setting, remove fish promptly and release non-target fish according to the approved animal ethics and permit requirements.

Bait is not required for this species because baited and unbaited traps produced similar catch rates in the cited study.

Trap mesh: Approximately 3 mm

Trap dimensions: Approximately 250 by 250 by 450 mm

Trap clearance: 15 to 45 minutes after setting

Survey methodology: 3. Use nets and direct observation

Use a 2.5 m seine net with 2 to 5 mm mesh, constructed from approximately 70 percent shade cloth, where the waterbody and banks allow safe seining.

Use hand-held dip nets and bait nets in dense aquatic vegetation, shallow margins and other accessible microhabitats.

Use direct observation and daytime snorkelling only where safe, authorised and suitable for the waterbody, and treat visual absence cautiously because visual censuses are not fully reliable for this species.

Seine length: 2.5 m

Seine mesh: 2 to 5 mm

Reported netting period: October to January

Survey methodology: 4. Time and identify surveys

Where practicable, survey from October to December when reported abundances were higher, while recognising that the species was collected in all months except July at the Noosa River.

Plan repeat or multi-season surveys where one visit cannot represent the fish assemblage or changing water conditions.

Have an experienced fish ecologist check identifications because Honey Blue-eye can be confused with Pacific Blue-eye and juvenile sand mullet.

Use clear side-on photographs and retain voucher or genetic material only where authorised and necessary, because visual identification can be unreliable.

Reported collection period at Noosa River: All months except July

Higher reported abundance: October to December

Successful netting period reported by ANGFA: October to January

Survey methodology: Minimum effort and reporting

  • Search all suitable and potentially affected waterbodies, including downstream waters and connected habitat, rather than relying on a single sampling point.
  • Use a combination of unbaited traps, seine or dip nets and direct observation where site conditions permit.
  • Record the date, start and finish time, method, trap or net location, waterbody, weather, water condition, effort, catch, photographs and identification confidence for every sampling event.
  • Document sites that could not be sampled, the access constraints and any conditions that reduced detection.
  • Submit confirmed records and negative survey results to the relevant Queensland wildlife database and any other relevant state or territory wildlife database.
  • Escalate a suspected Honey Blue-eye record to the project ecologist and relevant wildlife authority before habitat disturbance continues.

Before habitat disturbance: Avoid and minimise

Treat suitable wallum waterbodies and their vegetated margins as potential Honey Blue-eye habitat until survey results and approvals show otherwise. The species has a restricted, patchy distribution and many populations are isolated.

  • Avoid clearing or filling small streams, lagoons, lakes, swamps and dune lakes that contain suitable low-flow freshwater habitat.
  • Retain aquatic macrophytes, sedges, reeds, water lilies and vegetated margins that provide shelter and breeding habitat.
  • Prevent changes to water tables, flow paths, runoff, sediment loads, pollution and water quality at occupied or suitable sites.
  • Retain connections between adjoining suitable populations where practicable, because most reported populations are isolated from one another.
  • Keep access routes, machinery movements and public access away from known sites unless access is necessary and controlled.

Before habitat disturbance: Approvals and work planning

  • Check the current EPBC Act status and determine whether referral or approval is required before disturbing potential habitat.
  • Check Queensland threatened wildlife requirements, permits and any local waterway or protected-area approvals before surveying, capturing, handling or relocating fish.
  • Prepare a fauna management plan that identifies survey sites, exclusion areas, aquatic protection controls, authorised handlers, stop-work triggers and incident contacts.
  • Stage works so that the smallest practicable area of aquatic habitat is exposed at one time.
  • Schedule surveys and, where practicable, habitat disturbance outside the higher reported abundance period from October to December, subject to approval conditions and site-specific ecological advice.

Before habitat disturbance: Prepare the site

  • Complete the pre-clearance fish survey before machinery enters or alters suitable water habitat.
  • Mark retained waterbodies, vegetated margins, access routes, exclusion zones and any downstream protection areas on plans and on the ground.
  • Install exclusion fencing or other physical controls where they can keep machinery, sediment and people out of retained aquatic habitat without blocking fish movement or causing bank damage.
  • Brief machine operators and fauna spotter catchers on the species' appearance, habitat, handling limits, escape routes and stop-work procedure.
  • Confirm a lawful destination for any authorised relocation and arrange an aquatic wildlife veterinarian or wildlife carer contact before works start.

During habitat disturbance: Daily controls

Keep works out of retained aquatic habitat and its margins. A fauna spotter catcher must work with the site supervisor and machine operators, but must not replace the required fish survey, permits or water-quality controls.

  • Inspect exclusion fencing, sediment controls, water diversion structures and marked habitat before work starts each day and after heavy rain or any control failure.
  • Keep fuels, chemicals, concrete washout, spoil, sediment and contaminated water away from streams, lakes, swamps and drainage paths.
  • Maintain natural water levels and flow paths where practicable, and stop work if pumping, diversion or runoff is causing dewatering, turbidity, sedimentation or pollution in suitable habitat.
  • Keep machinery, vehicles and workers within approved access areas and prevent entry into retained aquatic vegetation and shallow margins.
  • Use weed and aquatic pathogen hygiene procedures between waterbodies to avoid transferring weeds, pathogens or introduced fish.

During habitat disturbance: Spotter catcher and machinery protocol

  • The fauna spotter catcher must remain in communication with the supervisor and operator and must have a clear view of the active work area and any water or wet margin being disturbed.
  • Direct the operator to stop before excavation, pumping, draining, infilling or vegetation removal enters an uninspected waterbody, wet margin or marked exclusion area.
  • Use hand tools or controlled inspection around shallow margins and aquatic vegetation where machinery could injure fish or damage retained habitat.
  • Do not allow a spotter catcher to enter unsafe water or operate outside their authority, training or permit conditions.
  • Record each daily inspection, exclusion-zone breach, control failure, fauna observation and corrective action.

During habitat disturbance: If Honey Blue-eye is found

  • Stop the activity that could injure the fish or disturb its waterbody and keep machinery clear until the project ecologist has assessed the find.
  • Do not capture, handle or relocate the fish unless the person is authorised and the activity is covered by the required permit, approval and animal welfare procedure.
  • Use the least intrusive method available to keep the fish in its waterbody, because the survey guidance notes that threatened fish are normally fully protected and do not normally need to be collected.
  • If authorised relocation is necessary, move the fish only to nearby retained habitat that is suitable, connected where practicable and approved in the fauna management plan.
  • Place an injured fish with an aquatic wildlife veterinarian or authorised wildlife carer, and document the transfer.
  • Resume work only after the ecologist or delegated authority confirms that the stop-work trigger has been addressed.

After habitat disturbance: Post-clearance checks

Leave retained water habitat protected after the active clearing or construction phase. Confirm that controls have worked and that any Honey Blue-eye record, injury or habitat impact has been reported.

  • Inspect the work area, retained aquatic vegetation, water margins, downstream waters and exclusion controls after clearing and after major rain events.
  • Check for stranded, injured or dead fish in dewatered areas, sediment ponds, diversion channels, excavations and isolated pools before removing temporary water controls.
  • Repair damaged fencing, sediment controls, banks and aquatic margins promptly and prevent further disturbance until repairs are complete.
  • Complete a follow-up survey where habitat was disturbed, water quality changed, fish were found, or the project ecologist considers detection or impact unresolved.

After habitat disturbance: Monitoring and reporting

  • Monitor retained and rehabilitated habitat for water level, flow, turbidity, sedimentation, pollution, aquatic vegetation condition and introduced Mosquito Fish.
  • Compare post-work observations with the pre-work habitat and survey records, including catch data and survey effort.
  • Report confirmed records, injuries, deaths, relocations, habitat damage, control failures and corrective actions to the relevant state wildlife database and approval authorities.
  • Review whether management actions are effective and adapt controls where monitoring identifies continuing threats.
  • Maintain exclusion fencing, access controls and water-quality measures until the project ecologist confirms that the site is stable and the controls are no longer needed.

After habitat disturbance: Offsets and residual impacts

  • Refer any unavoidable residual impact on occupied or suitable habitat to the approval process before works proceed.
  • Apply any approved offset, conservation agreement, reserve protection or other compensatory measure required by the relevant authority.
  • Give priority to protecting existing populations and maintaining adjoining populations where an approved conservation action requires population linkage or enhancement.

Rehabilitation actions: Restore water and vegetation

Rehabilitation should recreate the slow-flowing, freshwater wallum conditions used by Honey Blue-eye. It should restore aquatic shelter and breeding habitat while preventing introduced fish, weeds, sediment and altered hydrology from reducing habitat quality.

  • Reinstate natural drainage, water levels and low-flow conditions where construction has altered them, subject to the approved design and hydrological assessment.
  • Replant or allow recovery of local aquatic macrophytes, including emergent and submerged sedges, reeds and water lilies, along retained and restored margins.
  • Use local wallum vegetation appropriate to the site and avoid introducing plants, soils or water that could carry weeds, pathogens or non-native fish.
  • Restore sandy or muddy bottom conditions where they were unnecessarily covered or compacted, while preventing sediment from entering retained water.

Rehabilitation actions: Control threats

  • Control Mosquito Fish, Gambusia holbrooki, through an approved regional or site management plan and prevent their spread between waterbodies.
  • Control weeds with methods and chemicals that do not cause a significant adverse impact on Honey Blue-eye or its aquatic habitat.
  • Maintain sediment, erosion, runoff, pollution and access controls until water quality and banks have stabilised.
  • Protect restored sites from unauthorised collection, aquarium fishing and other access that could disturb fish or vegetation.

Rehabilitation actions: Monitor success

  • Set monitoring points in restored habitat and nearby retained habitat so changes in water level, pH, water colour, conductivity, flow, aquatic vegetation and sediment can be compared.
  • Repeat fish surveys using the approved combination of traps, seines, dip nets and direct observation, with effort and timing recorded for every visit.
  • Use October to December monitoring where practicable because higher abundance was reported in those months, while considering the species' reported collection in most months of the year.
  • Treat successful rehabilitation as restored suitable habitat with stable water conditions, dense aquatic shelter, no project-related pollution or sedimentation, and confirmed use by Honey Blue-eye or a documented management response where fish are not detected.
  • Report monitoring results to the project regulator and relevant state wildlife database, and adapt weed, Mosquito Fish, hydrology or access controls when results show continuing threats.

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