Gold – Zilla! Massive goldfish growing faster than anywhere else in the world!
It’s GOLD-zilla, massive TWO KILOGRAM mutations of the common house pet the goldfish are prowling Australian rivers – and they’re growing faster than anywhere else in the world.
Usually the former fairground favourites weigh a few grams but researchers have realised something fishy is going on in the Vasse River, south of Perth, in Western Australia.
Special teams have been using similar tagging technology used to track GREAT WHITE SHARKS to monitor the growing goldfish with acoustic tags which ping monitoring stations along the river with sound waves.
Teams have been stunned by the size of the specimens they’ve managed to pluck from the water and think larger fish could be out there.
It’s thought the goldfish in the Vasse River are gorging on algal plants which have perfect growing conditions in the slow warm water.
Dr Stephen Beatty, senior research fellow in the Freshwater Fish Group and Fish Health Unit at Murdoch University, Western Australia, said: “We think the reason they get so big is the productivity of the river system, there’s a huge amount of algal growth which the goldfish eat, and a slow flow rate which allows the heating up of the water.
“These goldfish in Australia have the fastest growth rate in the world. In our study these goldfish in comparison to the rest of the world are getting bigger quicker.
“We put acoustic tags on the fish, we basically have a series of listening stations up and down the river. When a fish passes within a few hundred metres of the stations it records that fish at that time, so we can build up a pattern of where the fish are.
“We think some of the fish are getting eaten, the big orange ones will be more vulnerable to birds and predators.
“Over the years they have been in the river some of the orange ones have been bred out because of this. They are the world’s oldest domesticated fish and we have bred them to be bright orange, but in the wild they quickly revert to the softer gold colour
“The worst invasive fish species we have is the eastern gambusia, it breeds early and often and they take the tail fins off native fish, if I was to click my fingers and get rid of a fish it probably wouldn’t be goldfish, it’d be the eastern gambusia.
“What goldfish are good at, particularly massive ones like these, they are a great flagship to draw attention to invasive species in Australia.”