First transmissible cancer found in fish in Canada
Scientists have confirmed the first instance of a transmissible cancer in a freshwater fish species, specifically affecting brown bullhead catfish in Lake Memphremagog. While the cancer is not a threat to humans, researchers advise against consuming infected fish.
Why it matters
This discovery is significant for marine biology and environmental monitoring, as the species serves as an indicator for water quality.
Cheryl Santa Maria Digital Journalist Published on Jul. 22, 2026, 6:11 PM The cancer poses no known health risk to humans.
A team of researchers from Vermont has identified what they say is the first-ever transmissible cancer in a freshwater fish species.
The disease presents as raised black skin lesions on brown bullhead catfish in Lake Memphremagog, a lake that shares a border with Quebec and Vermont.
The findings were published Wednesday in the journal Nature .
The researchers say the fish in Lake Memphremagog, which provides drinking water to more than 175,000 people, pose no health threat to humans.
"The cancer cells cannot infect or survive in another species, and the fish are safe to handle and study," the authors say in a statement .
That said, researchers advise against eating infected fish. About 30 per cent of the lake's brown bullhead population is believed to have the disease.
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