Review of the impacts of introduced ornamental fish species that have established wild populations in Australia

About the document

The introduction and spread of alien (non-native) species in various parts of the world is regarded by many as a major threat to global biodiversity and hence ecological sustainability. In Australia, introductions of species such as the cane toad, prickly pear, foxes, rabbits, and common carp are among the higher profile biological invasions. However, few people are aware that small, freshwater fish species, including some used as ornamental fish in ponds and aquaria, can also cause damage to Australian environments and species.

Many ornamental fish are brought into Australia each year for stocking into home aquaria or garden ponds and between 12 and 14% of Australians are thought to keep aquaria. It is inevitable that some of these ornamental fish end up in natural waterways and although many don’t survive, some have established feral populations. Accordingly, there has been a rise in the number of exotic freshwater ornamental fish species establishing wild populations in Australia over the past 20-30 years. Of the 41 alien fish species currently known to have established populations in Australia, up to 30 are now thought to have arrived in the country via the ornamental fish trade. This is a relatively large number of new species and there is growing concern over the potential for one or more of these to create an expensive environmental problem.

In summary, this review has identified a number of key issues for the future management of feral ornamental fish in Australia that need to be urgently addressed. The recent proliferation of wild populations of ornamental fish in Western Australia and Queensland is matched globally only by the high number of such species in the southern states of the USA. Although progress will clearly involve targeted education to change public perceptions about the dangers of ornamental fish, it will also require a nationally coordinated approach to stop the current situation from deteriorating further. In this respect, cooperation will be required between the various Federal and State management agencies as well as between State authorities because the spread of such fish within rivers will ignore State boundaries. There is a grave danger that one or more of these introduced fish species will become another pest like the common carp and create another legacy of degraded environments and costly controls.