Scientists Discover the First-Ever Contagious Cancer in Fish

Key Points:

• Researchers in Vermont discovered a contagious form of melanoma cancer affecting brown bullhead catfish in Lake Memphremagog, marking the first transmissible cancer found in fish and freshwater animals.
• Genetic analysis showed tumors from different fish were more similar to each other than to their hosts, indicating the cancer spreads like an infectious parasite rather than arising independently in each fish.
• This transmissible cancer is distinct from known causes like UV exposure or toxins, and has been found in multiple New England water bodies, suggesting it is widespread in catfish populations.
• The mode of transmission remains unclear, but it may occur during spawning when fish are in close contact or through environmental exposure; researchers also note high arsenic levels in tumors that could influence vulnerability.
• The discovery adds to the small number of known transmissible cancers in animals and offers a unique opportunity to study cancer biology and immune evasion, with potential implications for human cancer research.