Invasive goldfish are gobbling up natural resources.

Considering their staple status in two-bit pet stores, you probably don’t think that much about goldfish. Surely, such a small, non-carnivorous fish couldn’t possibly do much damage if it were let out into the wild? Well, that couldn’t be further from the truth; goldfish are a highly invasive species, and when let into wild waters, they have a tendency to completely take the place over in short order.

In recent months, goldfish have been discovered in large quantities and larger sizes throughout Canada, in both smaller stormwater ponds and larger bodies of water like the Hamilton Harbour in Ontario. Goldfish are absolutely voracious eaters, gobbling up whatever they can fit in their mouths, and as they release hormones and their bodies expand, that accounts for more and more food. Underwater plant populations get chomped, muscling other fish out of food.

The strange thing is that these habitats are already rather hostile even to the animals that are supposed to live there, yet the goldfish are more than capable of adapting.

These are not your average goldfish…

They’ve been found in Canada and they are causing all sorts of problems 🧵

— Euronews Green (@euronewsgreen) March 24, 2022

“These ponds are extreme environments,” biology professor Nick Mandrak of the University of Toronto Scarborough told the university’s magazine. “Not only is the water shallow, oxygen levels are extremely low and temperatures can reach 30-plus degrees in the summer.”

Scientists from Fisheries and Oceans Canada have been tracking the goldfish using accoustic tags to determine where they’re going and, hopefully, where they’re coming from.