Scientists have identified a transmissible melanoma spreading among brown bullhead catfish [3] in Lake Memphremagog, which straddles the Quebec-Vermont border [1].
This discovery is significant because it is the first known instance of a contagious cancer in a freshwater fish. It is also only the fourth contagious cancer identified in any animal species to date [4].
The disease manifests as a skin cancer that spreads between individual fish. Researchers noted that the melanoma cells are transmissible, allowing the cancer to move from one host to another [2].
Evidence suggests the disease has been present in the lake for more than a decade [5], with some reports indicating its presence since the early 2010s [5]. The long-term nature of the outbreak has provided scientists with a window into how these rare cancers persist in wild populations.
"The first-ever transmissible cancer to spread among fish in a freshwater setting has been discovered among brown bullhead catfish in Lake Memphremagog," a reporter for Fox4 News said [1].
While most cancers are the result of genetic mutations within a single organism, transmissible cancers involve the actual transfer of malignant cells between individuals. This phenomenon is extremely rare across the animal kingdom.
"Scientists confirmed a transmissible melanoma spreading among catfish in a U.S.-Canada lake, marking only the fourth contagious cancer ever found in animals," a science correspondent for MedIndia said [4].
Researchers continue to study the impact of the melanoma on the brown bullhead catfish population. The persistence of the disease for over 10 years [5] suggests a stable transmission cycle within the freshwater ecosystem of Lake Memphremagog [1].
“The first-ever transmissible cancer to spread among fish in a freshwater setting has been discovered”
The identification of transmissible melanoma in catfish expands the scientific understanding of how cancer can behave as an infectious agent. Because this is only the fourth known instance of contagious cancer in animals, studying the transmission mechanism in a freshwater environment may provide critical insights into the biological requirements for cancer to survive and spread between hosts, potentially informing research on other rare transmissible malignancies.
