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Tench (Tinca tinca)

Tench occurs in the Murray-Darling system and has also been reported in the Onkaparinga River. It may compete with trout and native fish for food, although the cited Australian account says it is not a serious threat to native fish.

Key facts

Type: Pest animal, fish.

Native to: Eurasia, including most of Europe and parts of Asia.

Established in: NSW, VIC, TAS, SA.

Other names: Tinca vulgaris, golden tench.

Identification

  • It has a thickset, heavy body that is compressed from side to side.
  • Its olive-green body can appear dark green or almost black, with golden reflections on the underside.
  • The skin is thick and slimy, and the small scales are deeply embedded.
  • Look for a small orange-red eye and a small mouth with thick lips and one pair of barbels, one at each corner.

Where it lives

In Australia, tench has been reported in the Murray-Darling system and in small numbers in the Onkaparinga River; it typically uses shallow, densely vegetated lakes and backwaters with weed and mud bottoms.

Why it matters

  • Tench may compete with trout and native fish for food, but the cited Australian account says it does not represent a serious threat to native fish.
  • Tench can prey on snails and other molluscs, and high predation may affect aquatic food webs and plant growth.
  • Tench can disturb bottom sediments and has been implicated in declining water quality.

How it spreads

  • Tench was introduced to the River Murray in 1876 and has spread through the Murray-Darling system; a small population has also been reported in the Onkaparinga River.
  • Bait-bucket introductions, flooding and natural range expansion are possible ways it can reach new areas.

Control methods

  • Contact the relevant state or territory fisheries or biosecurity authority for approved methods and advice on reporting sightings.
  • Do not move or release live tench into another waterway.
  • Any removal should use humane, approved methods and follow local regulations.

Site hygiene and welfare

  • Do not transfer live tench or bait between waterbodies, as bait-bucket introductions are a possible spread pathway.
  • Avoid moving water or aquatic material between sites, and clean and dry boats and fishing gear before using them in another waterbody.
  • 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: Prohibited matter. Report it to Biosecurity Queensland on 13 25 23 within 24 hours and do not move or deal with it. Everyone must also take all reasonable and practical steps to minimise its risks (the general biosecurity obligation).
  • New South Wales: Prohibited matter. It is an offence to deal with it, and you must notify NSW DPIRD as soon as you become aware of it.
  • Victoria: Not declared. Not declared under the Catchment and Land Protection Act 1994. Other Victorian laws may still apply.
  • 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: Not a declared pest. Not a declared pest or prohibited matter in Tasmania. Importing animals is still controlled by Biosecurity Tasmania.
  • 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.

  • New South Wales: Biosecurity Act 2015 (NSW), administered by NSW Department of Primary Industries and Regional Development
  • Victoria: Catchment and Land Protection Act 1994 (Vic), administered by Agriculture Victoria
  • Tasmania: Biosecurity Act 2019 (Tas), administered by Biosecurity Tasmania
  • South Australia: Landscape South Australia Act 2019 (SA), administered by the regional landscape board

Sources