Have you seen a spotted tilapia?

Spotted tilapia have been found in Far North Queensland in the Walsh River (north of Chillagoe) and near Bruce Weir (near Dimbulah, west of Mareeba).

If you see or catch a spotted tilapia in this area, please take a photo and report it online or call Biosecurity Queensland on 13 25 23.

Five sub-adult spotted tilapia with scale ruler (sub-adults still have bands on body)
© Queensland Government
Spotted tilapia: restricted noxious fish
© Queensland Government
Juvenile spotted tilapia (Tilapia mariae) captured from the Walsh River in October 2017
© Queensland Government
Mozambique tilapia: restricted noxious fish
© Queensland Government

Download the Mitchell and Walsh River catchment map (PDF, 409KB)

Tilapia were introduced into Australia in the 1970s as ornamental fish and are now a major threat to Australia's native biodiversity. Females carry their eggs and small fry in their mouths, and these can survive for a long time after the adult dies. Therefore, releasing living or dead fish into waterways can cause new infestations. Tilapia is a restricted noxious fish under the Biosecurity Act 2014.

Scientific name

Oreochromis mossambicus (Mozambique tilapia)
Tilapia mariae (Spotted tilapia)

Other names

  • Part of the Cichlidae family: Mozambique tilapia
  • spotted tilapia


O. mossambicus

  • Grows to more than 36cm.
  • Lives up to 13 years.
  • Usually dark grey or almost black but can be silver with 2–5 dark blotches/spots on the side.
  • Breeding males can have red tips on their fins.
  • Deep-bodied with a thin profile and long pointed fins.

T. mariae

  • Ranges from dark olive-green to light yellow.
  • 8 or 9 dark bars or blotches on the sides (obvious in younger fish).
  • Grows to 30cm.
  • Deep-bodied with a thin profile and long pointed fins.


O. mossambicus

  • Hardy fish, can survive temperatures between 8 and 42°C.
  • Requires temperatures of about 16°C to remain active and feed.
  • Can withstand high-saline waters and low-dissolved oxygen.

T. mariae

  • Less tolerant of cooler temperatures and therefore found at lower latitudes.


  • Established in Queensland.

Life cycle


  • Sexually mature at 3 years or less in favourable conditions.
  • O. mossambicus can become sexually mature at small sizes in poor conditions, or during times of overcrowding. Known as 'stunting', this results in large populations of mature fish with small bodies.
  • O. mossambicus are mouthbrooders. Females protect eggs and small fry from predators by holding them in their mouths. Males build large circular breeding nests in soft silt or muddy layers.
  • T. mariae lay their eggs on hard surfaces.


  • Diet is omnivorous.
  • O. mossambicus feed mainly on plankton, insects and weed but will take a wide variety of other foods.
  • T. mariae mainly eat plants.



  • Successfully invades and dominates many water habitats due to their high ability to reproduce and survive in very different conditions, and simple food needs.
  • Can rapidly outnumber native fish and dominate aquatic communities.
  • Can survive environments where native fish find coping difficult.
  • Unlike many native freshwater fish, tilapia can retreat downstream into highly saline waters during drought and move back upstream when conditions improve.
  • Affects native species as they compete for habitat and food, behave aggressively and disturb plant beds when building nests.


  • Loss of favourite fishing locations due to tilapia invading and destroying native fish populations. Tilapia can create large, monospecific (single species) fisheries.


How they are spread

  • Most new infestations are caused by human-assisted translocation (movement of live fish). This includes private dam stocking and moving tilapia between catchments to use as bait, or to create new 'fisheries'.
  • Biosecurity Queensland maintains a strict 'no-take' approach to manage tilapia and reduce the spread of this noxious fish.

Monitoring and action

  • If you catch tilapia in the wild, humanely kill them and do not return them to the water. Report all invasive fish captures through our online reporting form. Take photos, if possible, to show your catch.
  • Follow the ethical euthanasia code in Euthanasia of animals used for scientific purposes (PDF, 1.8MB), the 2001 Australian & New Zealand Council for the Care of Animals in Research and Teaching publication. The most appropriate way may be to stun the fish with a sharp blow to the back of the head, just above the eyes. When done correctly, this causes brain destruction—the fish's gill covers should stop moving and eyes should remain still.
  • Intensive fishing may reduce pest fish numbers in small enclosed waterbodies, but this practice alone is not an effective long-term control strategy.


  • Poisons can completely remove pest fish in ponds and small dams, but are not practical for rivers and streams as these poisons also kill native fish.

Legal requirements

  • Tilapia is a restricted noxious fish under the Biosecurity Act 2014.
  • You must not keep, feed, give away, sell, or release tilapia into the environment without a permit.
  • If you catch these species, you must immediately humanely kill and dispose of them by burying them above the high-water mark or disposing of them in a nearby bin.
  • By law, you have a general biosecurity obligation (GBO) to take reasonable and practical steps to minimise the risks associated with restricted noxious fish under your control.

Further information


General enquiries 13 25 23