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Oriental weatherloach (Misgurnus anguillicaudatus)

Oriental weatherloach is an introduced freshwater fish in Australia, where escapes and releases associated with fish farms, aquariums and live-bait use have contributed to established populations. It can affect native aquatic ecosystems by reducing prey and competing with native fish.

Key facts

Type: Pest animal, fish.

Native to: East and Southeast Asia.

Established in: QLD, NSW, ACT, VIC, SA.

Other names: Japanese loach, pond loach, Chinese weatherfish, dojo loach.

Identification

  • The body is long, eel-like and laterally compressed, usually about 15 cm long but reaching around 30 cm.
  • Colour ranges from brown to yellow, with greenish, grey-brown or black marbling and a paler underside.
  • The small, narrow mouth has 10 barbels, including four smaller ones below the lower lip.
  • Look for a dark spot in the upper half of the caudal-fin base and a short lateral line.

Where it lives

In Australia it inhabits freshwater rivers, lakes, ponds, swamps and other still or gently flowing waters, especially where the bottom is muddy or silty.

Why it matters

  • Experimental studies found significant reductions in macroinvertebrate numbers and biomass where the fish was present.
  • It is associated with elevated ammonia, nitrate and nitrite, and turbidity, which can reduce water quality.
  • It may compete with native fish for food, shelter and spawning sites, and prey on their eggs and juveniles.

How it spreads

  • The species is traded as an ornamental aquarium fish and live bait, and introductions have been linked to these pathways.
  • Escapes from fish farms are also believed to account for many introductions; its environmental adaptability and reproductive capacity can aid establishment and spread.

Control methods

  • Seek advice from the relevant state or territory fisheries and biosecurity authorities before attempting removal, and use only permitted methods.
  • Where feasible and authorised, use targeted trapping or netting; established populations may need specialist assessment and approved removal methods.
  • Do not release, transfer or use captured fish as bait, and dispose of them as directed by authorities.
  • Check treated sites again for remaining fish and report suspected new populations to the relevant state or territory biosecurity agency.

Site hygiene and welfare

  • Before moving between waterways, drain water from boats, buckets and other equipment, and clean and dry nets, footwear and gear.
  • Do not transfer fish, water, mud or aquatic material between sites.
  • Use methods set out in the national model codes of practice and standard operating procedures for the species.
  • Coordinate control with neighbours and the local government biosecurity plan, as isolated effort is quickly undone by reinvasion.

Classification by state

  • Australia (national): No national listing. Managed under state and territory law.
  • Queensland: Restricted matter, categories 3, 4, 5, 6, 7. Do not give it away, sell or release it into the environment; do not move it; do not keep it; do not feed it; kill it and dispose of it. Everyone must also take all reasonable and practical steps to minimise its risks (the general biosecurity obligation).
  • New South Wales: Notifiable aquatic pest. It must not be possessed, bought, sold, moved or released in NSW, and you must notify NSW DPIRD within one working day of finding it. The general biosecurity duty applies: anyone dealing with it must prevent, eliminate or minimise the risk it poses.
  • Victoria: Noxious aquatic species. Declared a noxious aquatic species under the Fisheries Act 1995, so it must not be brought into Victoria, kept, sold, moved or released into waters. Report any sighting to the Victorian Fisheries Authority on 13 FISH (13 3474).
  • South Australia: Noxious species. Declared a noxious species under the Fisheries Management Act 2007, so it must not be brought into South Australia, kept, sold or released, and it must not be returned to the water alive. Report any sighting to PIRSA FISHWATCH on 1800 065 522.
  • Western Australia: Noxious fish. Prescribed as a noxious fish under the Fish Resources Management Regulations 1995, so it must not be brought into WA, kept, sold or released. Report any sighting to FishWatch on 1800 815 507.
  • Tasmania: Declared pest. It is a declared pest under the Biosecurity Act 2019 (Tas). Report sightings to Biosecurity Tasmania and follow any management requirements.
  • Northern Territory: Not a declared pest. Not on an NT declared or prohibited list. Check with the NT Government before keeping, moving or releasing it.
  • Australian Capital Territory: Declared pest, prohibited. It is a declared pest throughout the ACT. Dealing with it, such as selling, moving or keeping it, is prohibited.

Legal obligations

Every state and territory places a duty on landholders and people working on land to prevent the spread of invasive species, such as the general biosecurity obligation in Queensland and the general biosecurity duty in New South Wales. Declarations and control requirements differ between states and local government areas, so check the current official list before work starts.

  • Queensland: Biosecurity Act 2014 (Qld), administered by Biosecurity Queensland (13 25 23)
  • New South Wales: Biosecurity Act 2015 (NSW), administered by NSW Department of Primary Industries and Regional Development
  • Australian Capital Territory: Biosecurity Act 2023 (ACT), administered by ACT Biosecurity
  • Victoria: Catchment and Land Protection Act 1994 (Vic), administered by Agriculture Victoria
  • South Australia: Landscape South Australia Act 2019 (SA), administered by the regional landscape board

Sources