Ottawa will cull thousands of feral goldfish from a stormwater pond after crews removed about 5,000 fish earlier this year; officials estimate up to 1,000 remain. Councillor Riley Brockington described the roughly 6,000 figure as "mind‑blowing," and experts warn the true population may be much larger because of unseen juveniles. Goldfish reproduce rapidly, can grow very large, harm native species by increasing turbidity, and thrive in warming waters. Authorities urge pet owners not to release aquarium fish into waterways.
Ottawa to Cull Thousands of Feral Goldfish After 'Mind‑Blowing' Infestation in Stormwater Pond
Ottawa will cull thousands of feral goldfish from a stormwater pond after crews removed about 5,000 fish earlier this year; officials estimate up to 1,000 remain. Councillor Riley Brockington described the roughly 6,000 figure as "mind‑blowing," and experts warn the true population may be much larger because of unseen juveniles. Goldfish reproduce rapidly, can grow very large, harm native species by increasing turbidity, and thrive in warming waters. Authorities urge pet owners not to release aquarium fish into waterways.
05:53 AM, 11/21/2025Environment
City officials in Canada's capital plan to cull thousands of feral goldfish from a stormwater pond after crews discovered a large, rapidly expanding invasive population.
Earlier this year, staff removed about 5,000 fish from Celebration Park; officials estimate as many as 1,000 may still remain. Councillor Riley Brockington, who represents the area, called the roughly 6,000-count "mind‑blowing."
“The fact that we’ve had approximately 6,000 fish in this pond, in this year, is mind‑blowing,”
Female goldfish are highly prolific: a single mature fish can produce more than 100,000 eggs. Steven Cooke, a biology professor at Carleton University, said the visible shoal may represent only a fraction of the true population and warned there could be millions of tiny, undetected juveniles in the water.
Originally native to Asia and widely kept as aquarium pets, goldfish become a management problem when owners intentionally release them into urban ponds and waterways. In larger, warmer bodies of water they can grow very large, face few predators and reproduce rapidly. Their feeding and rooting behavior stirs up sediment, increasing turbidity and damaging aquatic plants and native species.
Warming water temperatures linked to climate change have made previously inhospitable waterways more suitable for goldfish, allowing them to spread through local streams and into larger systems such as the Great Lakes. Authorities in Canada and the United States have repeatedly urged aquarium owners not to release pet fish; in Minnesota, officials removed nearly 50,000 goldfish from local waters and warned that fish released at 2–3 inches can grow to more than 1 foot.
Shelby Riskin, an ecologist at the University of Toronto, said stormwater ponds have increasingly become breeding grounds for discarded goldfish, complicating restoration of native habitat. “There’s one in the Don Valley that at times seems no larger than a puddle — and yet at certain times of the year it’s just filled with goldfish,” she said.
Goldfish tolerate turbid, low‑oxygen conditions and often outcompete native species in those environments, making eradication and habitat recovery difficult. The scene of litter‑strewn ponds and thriving feral populations, Riskin said, is a vivid reminder of how resilient invasive species can be — a sentiment that evokes the famous Jurassic Park line about life finding a way.
What officials are urging: Do not release aquarium fish into the wild. If you can no longer care for a pet, contact local shelters, aquarium clubs, or pet stores for rehoming options.