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. Its common name refers to its aggressive nature and strong facial features, likened to that of the famous 1920s boxer Jack Dempsey.
Distribution
The fish is native to freshwater habitats from southern Mexico to Honduras, where it is found in slow-moving waters, such as swampy areas with warm, murky water, weedy, mud- and sand-bottomed canals, drainage ditches, and rivers.
Ecology
The Jack Dempsey natively lives in a tropical climate and prefers water with a pH of 6–7, a water hardness of 9–20 dGH, and a temperature range of . Males can reach up to 10 inches (25 cm) in length. It is carnivorous, eating worms, crustaceans, insects and other fish. In the wild they are found in warm murky water including mangroves and the lower reaches of rivers and streams.
Cichlids also have the potential to introduce disease into wild fish populations. Many pathogens and parasites have been recorded in imported ornamental fish in quarantine and post-quarantine in Australia.
Social and economic impacts include the costs of control, impacts on recreationally valued fish, including the spread of disease.
In the aquarium
thumb|A dim light and dark substrate will bring out the colors of the Jack Dempsey.The fish is a popular aquarium fish, due to its striking appearance and personable mannerisms. It, like most cichlids, is considered "aggressive", and have been shown to have a significant impact on Australian aquatic ecosystems. They highlight the importance of preventing the importation of invasive fish species because they are extremely difficult or impossible to eradicate once they become established in the wild.
In Australia, they are a popular aquarium fish typically sold to tropical freshwater tanks, although their aggressive nature means they 'are not suitable for community tanks'. However, the process has not yet been listed as a KTP, and several hundred aquarium fish species continue to be permitted for import into Australia, including more than 250 freshwater species. In 2004–05 alone, 15 million fish were imported.
According to experts, a large part of the problem stems from inadequate import assessments and controls. 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'.