It's fish to fish transmission, people. https://t.co/b4uWT1ynOG
— Alyan! (@AlyanWh) July 23, 2026
It’s rare that cancerous tumours can spread from one individual to another. But a genetic study suggests that’s what’s happening with melanoma tumours among catfish in Quebec and the northeastern U.S.
The discovery represents the first known transmissible cancer in fish and one of very few transmissible cancers ever found, reported the study published in the journal Nature on Wednesday.
Julie Dragon, co-leader of the new study, noted that only three other transmissible cancers have ever been identified so far — in Tasmanian devils, dogs and shellfish.
“These conditions are incredibly rare in nature,” she said. “So something has to be happening to allow this to happen.”
https://www.cbc.ca/news/science/fish-transmissible-cancer-9.7279045
Brown bullhead catfish melanoma represents a novel transmissible cancer