Tilapia

Tilapia is a noxious fish species under the Queensland Biosecurity Act 2014. Their habitats vary and include reservoirs, lakes, ponds, rivers, creeks, drains, swamps and tidal creeks. The fish are usually found over mud bottoms, often in well-vegetated areas. If caught, do not return them to any water body.

Two species are established in Queensland – the Mozambique tilapia (Oreochromis mossambicus) and the spotted tilapia (Tilapia mariae).

Mozambique tilapia grows to more than 36 centimetres, but are usually around 20 centimetres. They live up to 13 years. They have 3 anal fins and an elongated pointed snout. Their colour varies but they are often dark grey or almost black (but can be silver), with 3 black spots on the side. Breeding males can have red tips on their fins.

Spotted tilapia also have 3 anal fins, but have a short, rounded snout. Their colour ranges from dark olive-green to light yellowish green. They have 2 to 6 large black spots along the middle of their sides – more evident in younger fish. They can reach 30 centimetres but, in Australia, seldom get to 24 centimetres.

These fish feed mainly on aquatic vegetation, are prolific breeders, laying between 100 and 1700 eggs. They guard their young within their mouths until about 3 weeks after hatching.

Mozambique tilapia is found in northern Queensland and South East Queensland, particularly in reservoirs in the Brisbane area. On the Gold Coast, they have invaded the Albert, Pimpama, Coomera and Nerang river catchments.

Tilapia problems

The negative impacts tilapia have on our environment include:

• outcompeting and replacing native fish
• reducing the quality of spawning habitat available for native species
• increasing water turbidity
• uprooting aquatic vegetation
• altering erosion patterns
• increasing bank instability
• introducing new diseases to native fish populations.

Mozambique tilapia can limit their physical size (‘stunt’) and mature at an early age. This means they can build their population faster than native fish that can't reproduce at the same rate. This and their aggressive behaviour explain how tilapia can quickly exclude native fishes and become the most dominant fish species.

Methods of control

Controlling pest fish species such as tilapia is difficult. The most effective method is to prevent them becoming established in new waterways. Pest fish management is limited to:

• modifying the habitat (that is, manipulating water levels)
• physically removing them through electrofishing
• netting and screening
• using chemical (pesticides).

If you catch or see tilapia, report it to the Queensland Department of Agriculture and Fisheries using their online reporting form.

Mozambique tilapia in Robina West Lake

A report for the City of Gold Coast by Griffith University investigated the use of electrofishing to reduce the impact of Mozambique tilapia in Robina West Lake. Download a copy of this report below.

Managing invasive fish species - Mozambique tilapia in Robina West Lake(PDF, 18MB)

Gold Coast Pest Fish Classic

The Gold Coast Pest Fish Classic is the biggest pest fishing event in South East Queensland.

It is run jointly by City of Gold Coast and My Catch Australia. First launched as Tilapia Busters in 2015, this free event is helps raise awareness of the devastating effect pest fish have on the Gold Coast environment.

Details for the next Gold Coast Pest Fish Classic will be posted at What's On Gold Coast.