Transmissible Cancer Found in Brown Bullhead Catfish in Lake Memphremagog
Scientists have identified the first known transmissible cancer in a freshwater fish. The disease, a melanoma, spreads when living tumor cells move directly between brown bullhead catfish (Ameiurus nebulosus) in Lake Memphremagog, which straddles the US‑Canada border.
Lesions were first observed in 2012 and surveys between 2014 and 2017 found that roughly 23‑37 % of the catfish sampled carried the tumors. Genomic analysis showed that tumor cells from different fish are far more similar to each other than to their hosts, indicating a single transmissible lineage.
The research team, including Julie Dragon and Peter Emerson of the University of Vermont, published their findings in *Nature* in July 2026. No evidence suggests the cancer can infect humans. The discovery adds a fourth known transmissible cancer and the first recorded in a freshwater ecosystem, offering a new model to study cancer evolution and metastasis.
Entities: Brown bullhead catfish (Ameiurus nebulosus) · Julie Dragon · Lake Memphremagog · Nature · Nature (journal) · Peter Emerson · University of Vermont
Claims
What the coverage asserts, and how well corroborated each claim is across sources.
- [● 10 SOURCES] The first lesions were observed in 2012 in Lake Memphremagog on the US‑Canada border. (multiple articles)
- [● 10 SOURCES] The study reporting the transmissible cancer was published in the journal Nature. (multiple articles)
- [● 10 SOURCES] There is no evidence that the transmissible cancer can infect humans. (multiple articles)
- [● 10 SOURCES] The cancer is a melanoma that spreads via living tumor cells moving directly between fish. (multiple articles)
- [● 10 SOURCES] Researchers identified a transmissible cancer in brown bullhead catfish (Ameiurus nebulosus). (multiple articles)
- [● 10 SOURCES] The discovery adds a fourth known transmissible cancer and is the first recorded in a freshwater ecosystem. (multiple articles)
- [● 10 SOURCES] Approximately one‑third of brown bullhead catfish in the studied lake are affected by the tumors. (multiple articles)
- [● 10 SOURCES] Genetic analysis showed tumor cells from different fish are more closely related to each other than to their hosts, indicating a single transmissible lineage. (multiple articles)