Scientists Discover Fish Cancer with 'A Life of Its Own'

In Lake Memphremagog, straddling Vermont and Quebec, researchers have identified the first known transmissible cancer in fish. Since 2013, brown bullhead catfish have exhibited dark, tumorous lesions on their skin, with over a quarter of the population affected. This condition, initially mistaken for environmental toxin exposure, was revealed through genome sequencing to be a contagious cancer. The tumors' genetic makeup differs significantly from the host fish, indicating they are clones spreading between individuals. Scientists hypothesize transmission occurs during spawning, possibly through physical contact. This discovery is significant as it provides a unique model for studying how cancers metastasize and spread, potentially offering valuable insights into human cancer development and treatment. Researchers are also investigating historical observations that might indicate earlier instances of this phenomenon.