Fauna Spotters logo

Drysdale Gudgeon (Hypseleotris notata)

The Drysdale gudgeon (Hypseleotris notata) is a small freshwater fish known from the Drysdale River system in the Kimberley, where it is associated with rocky pools and slow-flowing streams. It is a WA Priority 2 taxon, so works near suitable waterways warrant careful assessment. Its ecology and current distribution are poorly known.

Conservation status

Western Australia, WA Threatened and Priority Fauna List: Priority 2.

Seasonal knowledge

Activity and breeding months have not been documented for the Drysdale gudgeon. The row below is a planning window only, not a species-specific seasonal pattern.

Breeding season: Not recorded.

Seasonal activity: Not recorded.

No species-specific seasonal information is available.

  • Precautionary habitat checks: Planning window only. Assess potential habitat whenever works may affect rocky pools or slow-flowing streams; no species-specific seasonal window is known.

Identification: Appearance and size

The Drysdale gudgeon has a few described visual characters, but the species is poorly known. Confirm identification with a suitably experienced fish ecologist.

The fish is light brown to purplish, with a whitish belly. Dark brown to black bars run along the sides and become V-shaped towards the rear.

It is reported to reach 4 cm in length.

Identification: Similar species

Diagnostic comparisons with similar gudgeons have not been documented. Do not rely on colour or size alone for a definitive identification.

Identification: Field signs

No distinctive tracks, nests or other field signs have been documented. A fish observed in water is not enough by itself to confirm this species.

Distribution: Known range

Records and published accounts indicate a very restricted, poorly documented range in the Kimberley.

The species is known only from the Drysdale River system in the Kimberley region of northern Western Australia. Atlas of Living Australia records show three WA records in two distinct 0.1-degree locations, spanning latitude -14.7 to -14.5 and longitude 126.8 to 126.9.

Distribution: WA listing

The DBCA Threatened and Priority Fauna List dated 1 July 2025 lists the species as Priority 2 in the Kimberley. This is a DBCA priority category, not a listing under the Biodiversity Conservation Act 2016. The species has no national listing.

Habitat: Reported habitat

The Drysdale gudgeon is associated with rocky pools and slow-flowing streams. More detailed habitat requirements are poorly known.

The Drysdale gudgeon is found in rocky pools and slow-flowing streams in the Drysdale River system.

Habitat: Site context

Water depth, flow thresholds, water quality, vegetation and seasonal habitat changes have not been documented. Treat waterways that resemble the reported habitat as potential habitat for precautionary assessment, not as confirmed occupancy.

Foraging habitat: Diet and feeding

The species' diet and specific feeding locations have not been documented.

No diet, prey or feeding behaviour has been documented for the Drysdale gudgeon. Do not infer its diet from general accounts of the genus.

Foraging habitat: Precaution at works sites

Where works may affect rocky pools or slow-flowing stream habitat, retain the aquatic habitat and avoid unnecessary disturbance of the waterway while ecological advice is obtained.

Breeding habitat: Breeding information

Breeding sites, reproductive behaviour and breeding season have not been documented.

Spawning, eggs, nesting, young and the timing of reproduction have not been documented.

Breeding habitat: Planning precaution

Do not assume that any particular month is outside the breeding period. If works could affect suitable stream or pool habitat, seek advice from a fish ecologist before setting timing or disturbance limits.

Sheltering habitat: Shelter information

Sheltering behaviour and habitat have not been documented.

Specific shelter features, refuge behaviour and use of rocks or other cover have not been documented for this species.

Sheltering habitat: Waterway precautions

Avoid removing or rearranging submerged rocks and other in-stream features in potential habitat unless the work has been assessed and authorised. This is a precautionary measure, not a claim about species-specific shelter use.

Threats: Known information

Specific threats to the Drysdale gudgeon have not been identified.

The species' restricted known range and scarcity of records mean its current distribution and status are poorly understood.

Threats: Works-site risk

Assess potential effects on rocky pools and slow-flowing streams case by case. Attribute a particular impact to the species only where supported by further evidence.

Survey methodology: 1. Desktop assessment

The species is known from very few records, and later surveys did not locate further specimens. A freshwater fish ecologist should lead survey design.

Review current records, project-area waterway mapping and ecological information for the Drysdale River system. Confirm whether rocky pools or slow-flowing stream habitat could be affected.

Survey methodology: 2. Field survey

Use appropriately qualified freshwater fish surveyors and methods authorised for the site. Record survey locations, habitat conditions, effort and any fish observations so that non-detections can be interpreted cautiously.

A reliable survey season, method and detection rate have not been established for this species. Do not treat a survey that does not detect it as proof of absence.

Vegetation associations

Source-checked associations and automatically indexed candidates are separated below. An association does not establish site presence, preference or dependence.

No species-specific vegetation association has been indexed or source-checked in this evidence library. This is an evidence gap, not evidence of no association.

Ecosystem associations

Source-checked associations and automatically indexed candidates are separated below. An association does not establish site presence, preference or dependence.

No species-specific ecosystem association has been indexed or source-checked in this evidence library. This is an evidence gap, not evidence of no association.

Soil and substrate associations

Source-checked associations and automatically indexed candidates are separated below. An association does not establish site presence, preference or dependence.

No species-specific soil association has been indexed or source-checked in this evidence library. This is an evidence gap, not evidence of no association.

Water and wetland associations: Water-associated habitat mentioned in profile

Source-checked associations and automatically indexed candidates are separated below. An association does not establish site presence, preference or dependence.

The Drysdale gudgeon is found in rocky pools and slow-flowing streams in the Drysdale River system.

Automatically indexed from existing profile text. Not a verified preference, mapped occurrence or habitat requirement. Check the original source and regional qualifiers before use.

Evidence: Unreviewed profile-derived candidate

Confidence: Not independently verified

Region: Scope as described in the quoted profile text; not independently verified. Profile states: WA.

Habitat use: general

Attribution gap: No sentence-level reference is attached to the original profile block. Review the profile bibliography; this candidate is not source-verified.

Fauna records and mapped habitat: Not yet analysed

Record locations can be overlaid with mapping, but record frequency alone does not measure habitat preference. No species is excluded from desktop assessments by this analysis.

No quality-controlled record-to-map analysis has been completed for this species. The existing generalised distribution dots and indicative range polygons have not been treated as precise occurrence coordinates.

A defensible run needs dated, independently attributable records, coordinate uncertainty, duplicate and captive-record checks, layer versions and regional scope. Preference and absence require additional survey-effort and detection evidence.

Habitat limitations and contrary evidence: No supported exclusion recorded

Not recorded is not the same as cannot occur. Low suitability, resident habitat, breeding habitat and occasional movement are different conclusions.

This library has not established a vegetation, ecosystem or soil-type exclusion for this species. This does not mean all habitat is suitable; the evidence needed to justify an exclusion has not been assembled.

Habitat limitations and contrary evidence: Before using a negative association

  • Confirm the taxon, geographic region, life stage and habitat function covered by the evidence.
  • Check survey methods, season, repeated effort and detectability before interpreting non-detection.
  • Investigate credible contradictory records and microhabitats absent from broad mapping.
  • Do not convert a missing map class, low record count or failed data request into species absence.

Before habitat disturbance: 1. Confirm the footprint

Plan works with the known habitat description and uncertainty in mind.

Map all works, access routes and waterway crossings near rocky pools or slow-flowing streams. Have a freshwater fish ecologist assess potential habitat and advise whether targeted surveys or additional approvals are needed.

Before habitat disturbance: 2. Brief the crew

Explain the species' reported appearance and the limits of field identification. Set clear procedures for stopping work and contacting the environmental lead if an unfamiliar small fish is found in potential habitat.

During habitat disturbance: 1. Protect aquatic habitat

Avoid unnecessary disturbance to potential aquatic habitat and respond cautiously to fish observations.

Keep works within the approved footprint and prevent avoidable disturbance, sediment release or debris entering nearby pools and streams. Follow project controls and the advice of the responsible ecologist.

During habitat disturbance: 2. Respond to observations

If a potentially relevant fish is found, pause the activity that could affect it and contact the environmental lead or fish ecologist. Do not handle, collect or relocate fish unless the action is authorised and directed by a suitably qualified person.

After habitat disturbance: 1. Inspect and record

Check that controls have been maintained and document any effects or observations.

After works, inspect affected areas and nearby aquatic habitat for unplanned disturbance. Record observations, incidents and the condition of retained habitat in the project environmental records.

After habitat disturbance: 2. Escalate concerns

Report fish observations, habitat damage or control failures promptly to the environmental lead and seek advice from a freshwater fish ecologist. Do not assume the species is absent because no fish were observed.

Rehabilitation actions: 1. Restore the affected area

Species-specific rehabilitation requirements have not been documented. Guide restoration by site conditions and qualified ecological advice.

Reinstate disturbed areas in line with approved project plans, with particular care around rocky pools and slow-flowing stream habitat. Avoid adding, removing or rearranging in-stream features without ecological advice.

Rehabilitation actions: 2. Follow up

Document rehabilitation actions and any subsequent changes observed in the affected waterway. Monitoring periods and success criteria have not been specified for this species, so the project ecologist and relevant authorities should set them.

Sources