Jack Dempsey cichlids in Australia facts for kids
Quick facts for kids Jack Dempsey |
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Cichlasomatinae
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Rocio
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R. octofasciata
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| Rocio octofasciata (Regan, 1903)
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Jack Dempsey cichlids (Rocio octofasciata) are a type of fish often kept in aquariums. They are known for being quite aggressive, which is why they were named after the famous heavyweight boxer Jack Dempsey. These fish are naturally found in Central America. However, in 2004, a group of them was discovered in a flooded quarry in New South Wales (NSW), Australia. Even though people tried to get rid of them in 2004 and 2005, the fish are still there. Jack Dempsey cichlids are one of about 30 types of aquarium fish that have started living in Australian waterways. They can cause big problems for Australia's water environments. Their presence shows how important it is to stop invasive fish from being brought into a new area, because once they are established, it's very hard or even impossible to remove them.
Contents
What Jack Dempsey Cichlids Look Like
Jack Dempsey cichlids are a medium-sized fish. You can tell them apart from other cichlids by two dark grey or black stripes on the top of their head. These stripes go forward between their eyes. Their main body color is a dark blue. They also have many white or shiny blue spots on their fins, head, and body. You might also see dark stripes along their sides.
In Australia, these fish are popular pets for tropical freshwater tanks. However, because they are so aggressive, they are not good for tanks with many different types of fish. They can live for more than 10 years and can grow up to 25 centimeters (about 10 inches) long. They like water temperatures between 22 and 30 degrees Celsius (72-86°F). But they can also survive in colder water, as low as 8-10 degrees Celsius (46-50°F).
Jack Dempsey cichlids eat many different things. They will eat insects, worms, crayfish, snails, small fish, and even algae. In the wild, they live in warm, murky water. This includes areas like mangroves and the lower parts of rivers and streams. Female Jack Dempsey cichlids lay about 500 to 800 eggs at a time. Both parents protect the eggs. They become very aggressive towards other fish when they are protecting their young.
Where They Are Found in Australia
A group of Jack Dempsey cichlids was found in early 2004. This was in the Angourie area, near Yamba on the north coast of NSW. This group of fish lives only in an isolated flooded quarry. People in the area call it the ‘Green Pool’. There are no other known wild groups of Jack Dempsey cichlids in Australia. Since Jack Dempsey cichlids are popular pets, it is very likely that this group started from aquarium fish that were illegally released.
Attempts to Remove Them
When Jack Dempseys were first found in the Green Pool, the NSW Department of Primary Industries (DPI) thought they could be removed. This was because the pool was quite small and separate. It also had only a few native fish. So, three attempts were made to get rid of them between September 2004 and June 2005. They even used explosives! After the blasts, large Australian bass fish were put into the pool. These bass were meant to eat any young Jack Dempsey fish that might have survived.
However, follow-up checks by the NSW DPI showed that Jack Dempsey cichlids are still in the pool. It's possible some fish survived the attempts to remove them. Or, maybe they were put back into the pool on purpose. The NSW DPI has said that no more removal work is planned.
Why They Are a Problem
The same things that make cichlids popular pets also make them a problem when they get into the wild. They are tough, can adapt to different places, and have many babies. This makes them very good at taking over new areas.
Cichlids can take over native fish groups. They do this by being aggressive and competing for food and space. They eat almost anything smaller than themselves. This includes fish, small water creatures, and frogs. Since they are relatively large and aggressive meat-eaters, they could cause huge damage to native fish. This would happen if they spread to other waterways, like the nearby Clarence River.
Cichlids can also bring diseases to wild fish. Many germs and parasites have been found in aquarium fish brought into Australia.
There are also social and money-related problems. These include the costs of trying to control them. They can also affect fish that people like to catch for fun. And they can spread diseases to these fish.
Protecting Our Waterways
There are growing worries about importing aquarium fish like Jack Dempsey cichlids into Australia. More than two-thirds of non-native fish now living in Australia are thought to have come from the aquarium trade. Non-native fish species are linked to the decline of 42 percent of Australia's native fish. They also affect several frog species. Because of the big possible harm to biodiversity (the variety of life), the Australian Government's Threatened Species Scientific Committee said that bringing fish outside their natural areas met the rules for being listed as a "key threatening process." This means it's a major threat. However, this process has not yet been officially listed. Hundreds of aquarium fish species are still allowed to be imported into Australia. This includes over 250 freshwater species. For example, in just one year (2004-2005), 15 million fish were imported.
Experts say a big part of the problem comes from not checking imported fish well enough. For example, a big study of introduced aquarium fish in Australia found that checks are "based on information from overseas." This means they might not be good at predicting how they will affect Australian waters. Scientists have suggested that to help with disease control, the number of fish species allowed to be traded should be greatly reduced. Also, the number of places fish can come from should be much smaller. This would make it easier to find dangers, check risks, and control imported fish.
