Whopper Wanda tips scales to set New Zealand goldfish record

Otago Museum natural science curator Emma Burns with Wanda, the goldfish which went wild and grew to 2.4kg. Photo / Christine O'Connor

Meet Wanda.

Wanda used to be a bubbly, happy-go-lucky little goldfish — about the size of a pineapple lump - living in the comfortable surroundings of her plush fish bowl.

But then someone dumped her in a creek near Wanaka, and after several years of wandering the waterway, she grew into a 2.4kg "monster".

She was caught by a spearfisher. Her weight set a New Zealand spearfishing record for wild goldfish.

Otago Museum staff were so impressed with her horrifying size, they decided to have her taxidermied and put on display at the museum to highlight the environmental damage the fish can cause in New Zealand waters when they go wild.

Museum natural science curator Emma Burns said regular goldfish weighed between 90g and 270g.

"This one is a monster."

Wanda was one of two goldfish taxidermied by the museum. The other was black in colour and weighed about 1.9kg.

"It's quite interesting to see that they reach these large sizes.

"Once they reach these sizes, they become a little bit less familiar to people who are out there angling and fishing in Otago waterways."

Burns said the orange/gold colour we think of as typical goldfish was a fancy domestic characteristic that people had selectively bred for pet goldfish.

"So the black/bronze colour of the second whopper is the wild-type characteristic.

"When pet goldfish are released and breed, the generation's populations tend to revert back to black/bronze rather than orange/gold."

She said it was illegal to discard pet goldfish, and in the Wanaka area, the population was a growing problem for the Department of Conservation and Fish and Game.

"The fish graze on pond vegetation and burrow, disturbing water quality.

"There are also issues that when people liberating/dumping goldfish into freshwater systems, they also release lagarosiphon - oxygen weed - which is a pest plant species, too."

The fish will now be put in a quarantine freezer for up to four weeks. It was hoped it would be put on display in the museum at the start of next year.