Goldfish Invasion at Cootes Paradise Marsh

Article by Hugo Blue


HAMILTON—Spring 2014. It was a memorable night for Tys Theysmeyer along the Cootes Paradise marsh. It was the night of the goldfish invasion.

The head of natural lands at Hamilton’s Royal Botanical Gardens bore witness to a startling incursion, platoons of goldfish 30 meters long and 6 meters wide. What were once a few mercifully released house pets had transformed into gleaming battalions.

The invasion is in no way unique to Hamilton Harbour, but conditions in the water created opportunity for easy conquest. The goldfish, aka the cockroach of carp, is capable of feeding off algae other fish cannot, and a big appetite is goldfish standard issue.

Furthermore, the goldfish forces encountered little resistance, as numbers of rival carp in the area had been exhausted by previous engagements with humans.

After years of witnessing the goldfish wars, Mr. Theysmeyer notes, purely scientifically, how remarkable it is that any fish can survive in such inhospitable conditions. But he adds ominously that the ultimate solution is “fixing the water” to support “the right kind of fish.” Oh dear.

Cleaner waters would reinforce the indigenous fish population, probably by giving them nutrients and drone support, thereby enabling them to repel the invaders. This would effectively turn the carp conflict into a proxy war.

At least we’re bringing this struggle up to modern standards.

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