The Jack Dempsey (Rocio octofasciata) is a species of cichlid fish that is native to freshwater habitats from southern Mexico to Honduras, but also introduced elsewhere.

[3][4][5] Its common name refers to its aggressive nature[6] and strong facial features, likened to that of the famous 1920s boxer Jack Dempsey.

[4] It is also established as an introduced species in Australia, the United States and Thailand (presumably as an aquarium escapee) These are locally known as the Mexican Blue Frontosa.

In the wild they are found in warm murky water including mangroves and the lower reaches of rivers and streams.

[9] The features that make cichlids popular pets are also those that contribute to their invasive potential: ‘they are hardy, adaptable and breed prolifically’.

[10] Cichlids have the potential to dominate native fish populations through their aggressive behaviour and competition for food and space.

As relatively large and aggressive carnivores they could have devastating impacts on native fish populations if they spread to other waterways, such as the nearby Clarence River.

[10] Jack Dempseys lay their eggs on a flat hard surface within their territory, such as rocks, logs, or the glass bottom of an aquarium.

[10] Because Jack Dempsey cichlids are popular pets there is little doubt that this population established from illegally released aquarium fish.

Large Australian bass were then released into the pool to prey on any remaining larvae or juveniles that were not killed by the blasts.

For example, an extensive review of introduced aquarium fish in Australia concluded that assessments are ‘based on information obtained overseas and are likely to be of limited value in predicting the likelihood of environmental impacts in Australian waters’.

[13] In assessing the case for revised import controls – particularly in the context of introduced diseases, scientists recommended that ‘the number of species traded and the number of sources permitted need to be dramatically reduced to facilitate hazard identification, risk assessment and import quarantine controls.’[12]