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Published: 2010-05-11 00:00:00

The chance finding of a single Amazonian snail in the Waikato River has prompted a warning for aquarium owners to be careful about where they put the contents of fish tanks.

The apple snail, a native of South America’s Amazon river, is sold in pet shops as a fish aquarium accessory. It is not currently regarded as a pest in this country.

However, "escapes" into the wild in various tropical and sub-tropical countries have created problems in river systems, wetlands and lakes as the snails can be "voracious" plant eaters, potentially destroying food and habitat for native species if they get numerous enough, says Environment Waikato freshwater scientist Kevin Collier.

Dr Collier, who by chance recently found the lone apple snail in the Waikato River at Swarbrick’s Landing off River Rd in Hamilton, said that while conditions there were not ideal for this species, and further sampling has not turned up any more snails, there are other parts of the river and other places in the Waikato where this snail might be able establish populations.

"I would encourage people not to throw snails or other aquarium contents into waterways, lakes or wetlands as there is the possibility the apple snail and some other aquarium species could get established in warmer areas and increase the risks faced by native life.

"Besides damaging underwater habitat and areas of shelter areas for aquatic life, apple snails can also eat eggs of native animals and compete with species that feed on decaying plants. "