Fourth Contagious Cancer Found in Lake Fish

A groundbreaking study has identified a fourth naturally occurring contagious cancer, this time in brown bullhead catfish inhabiting Lake Memphremagog, which straddles the Canada-U.S. border. The research, published in Nature, details aggressive melanomas that spread between individual fish. This discovery is significant not only for understanding cancer as a breakdown of cellular cooperation but also for its potential to illuminate methods for preventing organ transplant rejection.

Researchers found that the immune systems of the affected catfish do not reject the foreign cancer cells, a crucial observation for transplant science. Genomic analysis revealed that these melanomas originated from a distantly related fish. This finding supports the theory that cancer is fundamentally a failure of multicellular cooperation, with cells behaving parasitically and invading new hosts.

This instance follows previous documented contagious cancers in dogs, Tasmanian devils, and mollusks. The study's authors speculate that the catfish cancer cells might spread through the aquatic environment, entering new hosts via gills, skin, or mouth. The research opens new avenues for understanding how cancers can transcend individual organisms.