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The 25cm goldfish found by a pair of Blenheim schoolboys in one of the Taylor River inlets last week underlines the risks that ornamental fish and aquarium weed pose to our natural waterways.
Marlborough ratepayers foot the bill for tens of thousands of dollars in weed control in the Taylor and Opawa Rivers each year – all because in the past someone has emptied their aquarium into the river and the weed has spread.
Goldfish have been seen in the rivers and in the waters of the Taylor Dam. Goldfish are relatively benign as they are vegetarians but the fear is that our waterways may be hosting the high-risk species Gambusia and the carnivorous Koi Carp and Rudd. These species are all banned from sale in New Zealand. Goldfish look very similar to juvenile Koi Carp and Rudd and to the untrained eye they may be mistaken so all goldfish found in the wild should be identified by Council or DOC staff just to make sure that they are not Koi Carp.
If Gambusia, Rudd or Koi Carp were to get established in Marlborough waterways, it could devastate our whitebait fishery.
It’s important that people realise that introduced fish and weed pose a serious threat in the wild, says Council fisheries scientist Peter Hamill.
“People may still have banned aquarium plants such as hornwort, parrot’s feather and Senegal tea in their tanks. Some people are unaware of the risk and the fish get traded and plant cuttings are swapped. Unfortunately, we know from experience that sometimes these undesirable species get dumped and end up in our rivers. People need to understand that these aquarium weeds spread fast, causing big problems in our waterways,” he says.
“The message is clear: don’t flush away unwanted fish and don’t dump fish or weeds directly into the drains or the rivers and streams.”
Any unwanted fish and aquarium plants can be bought to the Council for disposal. They may also be put into the compost or put out in the household rubbish collection.