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  ABC 18 May 07
Aquarium fish 'threaten biodiversity'
Anna Salleh
ABC Science Online

The millions of exotic fish imported each year to fill Australia's aquaria and ornamental ponds are a ticking time bomb for the continent's biodiversity, say some experts.

And they say Australia will find it hard to protect itself unless international trade laws are reformed.

"There is no doubt that aquarium fish that are being imported into Australia every week carry pathogens that have the potential to cause severe ecological impacts," says the University of Sydney's Professor Richard Whittington, a specialist in the health of aquatic animals.

Whittington and Dr Roger Chong, of Queensland's Department of Primary Industries and Fisheries, report on the threat posed by ornamental fish, in an article published online ahead of print in the journal Preventive Veterinary Medicine.

Australia imports around 8 to 10 million ornamental fish each year, says Whittington, and they carry a "plethora of exotic pathogens and parasites recorded and not yet recorded".

Although Australia has some of the most stringent standards for importing ornamental fish, Whittington says they are not good enough. He points the finger at international trade rules that only allow a country to stop imports of ornamental fish where there is scientific data to back up the ban.

Whittington says the problem is that collecting information on fish diseases is " laborious and expensive" and most of the ornamental fish are imported from developing countries where disease surveillance is limited.

"Those [trade] rules need to be revised to enable us to protect ourselves," he says.

He says Australia needs to be allowed to stop importing fish whose diseases have not been studied.

Quarantine rules fail

According to Biosecurity Australia, imported fish must spend up to 21 days in quarantine. Fish are inspected on arrival and any diseased fish must be re-exported, destroyed or treated by the importer, a spokesperson says.

But Whittington says this system failed in 2003 when there was an outbreak of a viral disease from imported gourami fish. The gourami iridovirus killed 90% of Murray cod on a farm in Victoria and could have been devastating if it infected wild Murray cod, which is considered a threatened species, he says.

Fortunately, he says the farm did not discharge its effluent into a river, a common industry practice.

Whittington also says that inspecting fish on arrival into Australia doesn't pick up pathogens that aren't causing symptoms, including those that don't affect ornamental fish but are dangerous to natives.

And inspections won't be much use for new diseases that little is known about, he says.

A spokesperson for Biosecurity Australia says there is currently a review of quarantine policy for ornamental fish with regard to iridoviruses and the organisation is looking closely at Whittington and Chong's paper.

But Whittington says Australian regulators are always "one step behind" the latest threats because they have to wait until a problem occurs before they get the scientific data to prepare a risk analysis.

"It's after the event every time," he says.

Whittington says given the likelihood of problem diseases in imported ornamental fish, Biosecurity Australia should lobby internationally for Australia's right to use the precautionary principle where data is missing.

Biosecurity Australia's spokesperson says the organisation is actively involved in setting international standards for "robust science-based approach to quarantine".

"We would review quarantine policies in light of any new science that may become available," he says. But he says it is beyond Biosecurity Australia's role to comment on Whittington's call for a precautionary approach.

Long history of concern

Whittington says the Australian government has had concerns about the disease potential of ornamental fish back to the 1980s, after the bacterial pathogen Aeromonas salmonicida entered Australia with imported goldfish from Japan.

The disease spread as goldfish were used as bait and unwanted goldfish were disposed of into waterways, he says. Wild fish and fish on farms were infected and there was concern for Atlantic salmon farms in Tasmania.

His paper also describes how, in the 1980s, fighting fish imported from Singapore caused problems in wild eels and farmed rainbow trout.

"There are examples of 22 species of imported aquarium fish that have set up breeding populations in rivers in Australia," says Whittington. "These infectious diseases could be the straw that leads to the extinction of endangered species, like the Murray cod."
links
In Singapore, fish release is one of the activities that happen during Vesak Day.

Fewer people releasing animals into the wild during Vesak period
By May Wong ChannelnewsAsia 10 May 05

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