Pest fish in the Redlands

The creeks, dams, lakes and wetlands in the Redlands Coast are home for many freshwater species, including 17 native fish.

Our freshwater ecosystems are under threat from the introduction of pest fish. These three restricted pest fish species are adversely affecting our waterway.

• Tilapia (Oreochromis mossambicus)  
• Carp (Cyprinus carpio)
• Mosquito fish (Gambusia holbrooki).

Image of Tilapia (Oreochromis mossambicus)  

Once introduced into a waterway, these pest fish can quickly dominate and out-compete native fish for habitat and food whilst also preying on smaller native fish. The feeding and nesting habits of the Tilapia and Carp are also known to degrade water quality.

The introduction of pest fish and other threats, such as increased catchment nutrients and erosion, have resulted in a steady decline in the abundance and diversity of native freshwater fish in the Redlands Coast. This threatens the balance of our freshwater ecosystems and ultimately the health of Moreton Bay.

Help us control pest fish

There is no easy answer for our pest fish problem. These pests have become well established in our creeks, dams and wetlands and it would be impossible to eliminate them entirely.

There are five things that everyone in the Redlands Coast can do to help:

Stop the spread

Pest fish are mainly spread by people moving them between waterways. If you catch one, do not release it. Kill it humanely and dispose of it away from the water. 

It is unlawful to possess restricted pest fish, alive or dead, move them or use them as bait under the Biosecurity Act 2014. Penalties apply.

Please report any sightings or catches of pest fish to:

• Fisheries Queensland – telephone its 24 hour Fishwatch hotline on 1800 017 116
• Feral Scan – report a feral animal sighting online
• Department of Agriculture and Fisheries (DAF)- report a feral fish sighting.

Improve water quality

Pest fish thrive in poor water quality. They can tolerate low dissolved oxygen, water weed infestations and high levels of sediment in the water far better than our native fish. 

By improving catchment management, through actions such as decreasing pollutants (primarily nutrients and sediments), we can improve water quality and provide favourable conditions for native fish.

Improve native fish habitat

Our native fish have adapted to the natural state of Redlands Coast waterways. They prefer well shaded, cool water with plenty of diverse in-stream habitat structures. Conversely, pest fish species are well suited to open warm water with little structural habitat. 

We can restore our degraded creeks and dams to mirror natural systems that favour our native fish. Planting and maintaining creek and dam bank vegetation will provide shade and the cooler water preferred by native fish.

It is also important to retain timber in our waterways as this is crucial habitat for native fish and will provide refuge areas for natives from the territorial and predatory pest fish.

Line fishing of pest fish

Once suitable water quality and natural habitat are provided, removal of large bodied adult pest fish from a water body can help to even up the odds for native fish. 

Line fishing for carp and tilapia has been shown to significantly decrease populations of these pests. Bait such as worms and corn work well for these species. Bait trapping of juveniles using funnel traps may also be an option. 

All forms of netting (except landing nets and scoop or dip nets) are illegal in the freshwaters of Queensland. Remember to kill any pest fish caught humanely and dispose of them away from the water.

For details on freshwater fishing regulations, visit Queensland Department of Agriculture and Fisheries