Across the United States and Canada, pet fish remains an incredibly popular household pet option. Fish rank 3rd in both countries behind Dogs (1) and Cats (2) as the three most popular pets in the land.
One major issue that plagues pet ownership is there is no binding agreement of responsibility. People regularly abandon pets in the woods when they become too much to handle.
With regards to monster goldfish, this is a major problem when the goldfish outgrows its tank so the owner dumps it in a nearby pond or lake, or flushing them down the toilet (which makes them stronger). These monster goldfish transition from life in a home aquarium to an invasive species capable of cloning themselves and taking over lakes.
A recent report by Ashley Joannou of the CBC is sounding the alarm over these monster goldfish the size of footballs (see images here and here on Twitter).
The report about British Columbia says “thousands of large, invasive goldfish have multiplied in bodies of water around the province.” It goes on to say that a goldfish can release 50,000 eggs at one time and do this 3 times a Summer.
Furthermore, the female goldfish don’t need the males to reproduce. Natural Resource Sciences professor Brian Heise told the CBC:
“Females don’t even need a male (to reproduce). They have a special process called gynogenesis in which the female will get the sperm from a different kind of minnow … to start the eggs developing, even though they’re not fertilized. And so she produces clones of herself. So, they’re very good at spreading rapidly.”
It’s worth mentioning the ‘football size’ of some of these monster goldfish. It’s not the weakest and smallest of the species that is out there cloning itself, it’s the biggest and baddest goldfish in the land (genetically speaking) who were too big for tanks at home.
One would think that these monster goldfish would be ill-equipped to survive the Canadian Winter underneath frozen lakes. And one would be wrong to think that.
Reports of ‘flashes of gold’ through the ice in British Columbia north of Vancouver suggest these invasive goldfish are proliferating and thriving throughout the Winter.
In the fight against invasive monster goldfish, they have devised an interesting way to capture them: electrocution.
They call it ‘electrofishing’ and it involves ‘shocking’ the water by passing an electric current through it to stun the fish. They float to the surface and field biologists can then easily scoop them up with a net.
This process, however, is expensive according to the CBC and can cost around $10,000/lake for just a couple of days of work.
Canada’s invasive monster goldfish problem has been building for years
Stateside, I witnessed this phenomenon firsthand last Summer in Detroit. I was playing golf on a municipal course in Detroit and noticed what looked like a bag of orange golf balls dumped in the pond.
Upon closer inspection, it was actually a school of a few hundred tiny goldfish all swimming in a tight-knit school. Obviously, this was an invasive species there and dumped by someone discarding a pet at some point.
And it’s easier than expected for these invasive tiny goldfish to get spread around from lake to lake in the mouths or talons of predators like Osprey and Eagles. They can swoop in for a handful of goldfish thinking they’re grabbing one large fish only to grasp several small fish and then drop those in other bodies of water while flying.
It is worth noting that goldfish should never be flushed if/when discarding them as pets:
February 20th-26th was the 2023 National Invasive Species Awareness Week here in the United States. It has seen a resurgence in awareness around invasive species in neighboring Canada as well.