Scientists discover likely transmissible cancer in wild catfish

Scientists have identified the first known likely transmissible cancer in wild catfish, a discovery that adds a new chapter to the understanding of contagious cancers. The cancer, a form of melanoma, was found in brown bullhead catfish in a lake in North America. This marks only the fourth transmissible cancer known to science, joining rare examples in dogs, Tasmanian devils, and certain shellfish.

The affected catfish were discovered during routine monitoring, and researchers confirmed that the tumors in different individuals share identical genetic markers, indicating that the cancer cells are being passed from fish to fish rather than arising independently. The finding matters because transmissible cancers are extremely rare and can have significant impacts on wildlife populations, potentially threatening species survival if the cancer spreads widely.

The study, published in the journal Nature, details how the melanoma cells in the catfish contain a specific mutation that is consistent across all sampled tumors. The lake where the infected catfish were found has not been named in the initial reports, but the discovery raises questions about how the cancer spreads in an aquatic environment and whether it could affect other fish species.

Background from the source indicates that transmissible cancers were previously known only in dogs (canine transmissible venereal tumor), Tasmanian devils (devil facial tumor disease), and certain bivalves like clams. The catfish cancer is the first such case in a wild fish population. Next steps for researchers include studying the mechanism of transmission, assessing the prevalence in the lake, and monitoring for potential spread to other waterways. The discovery underscores the need for ongoing surveillance of wildlife diseases, as transmissible cancers could pose unforeseen ecological risks.