Fish tank owners are being warned to be careful where they empty them after a destructive South American snail was found in the Waikato River.
The Apple Snail, a voracious plant eater that can destroy underwater habitat and eat eggs of native species, was found by chance.
The Waikato Regional Council says conditions were not ideal for the snail and river have failed to find any more.
At present, the Apple Snail is not regarded as a pest in New Zealand.
The council says people are encouraged not to throw snails or other contents of aquariums into waterways, as it is possible non-native species could get established in warmers areas and increase the risks faced by native life.
