Contagious Cancer Found in North American Catfish
Researchers have discovered a transmissible melanoma in brown catfish in Lake Memphremagog, marking the first documented case of contagious cancer in a freshwater fish species. Genetic analysis revealed that the tumors share a common identity, suggesting the cancer spreads between individuals.
Why it matters
This discovery provides new insights into the evolution and transmission of cancer in wildlife, potentially impacting ecological health monitoring.
An international team of researchers has identified a transmissible melanoma in the brown catfish (Ameiurus nebulosus)—the first documented case in fish and also the first recorded in a freshwater ecosystem. Their findings were reported this month in the journal Nature.
An Impossible Pattern
The story began in 2012, when fishermen and biologists detected an unusually high number of catfish with black lesions in Lake Memphremagog, a body of water straddling Vermont and Quebec. Previous studies revealed that these spots were malignant melanomas, and that between 23 percent and 37 percent of the specimens examined had these tumors—an unusually high incidence for this species.
“That was surprising,” said Julie Dragon, a researcher at the University of Vermont and co-lead author of the study. “We wanted to know how a bottom-dwelling fish was getting a cancer we associate with exposure to too much sunlight.”
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