Contagious cancer discovered in freshwater fish in Quebec and U.S. lakes

A contagious cancer has been discovered spreading among freshwater fish in lakes in Quebec and the United States, marking the first known instance of a transmissible cancer in fish. The disease, a type of skin cancer, has been found in several species, including the common carp and the goldfish, and is believed to spread when fish come into direct contact with one another. Unlike typical cancers that arise from a host's own cells, this cancer is caused by a clone of cells that originated from a single infected fish and can be passed between individuals, acting more like a parasite than a traditional tumor. The findings, published in a recent study, highlight a rare phenomenon previously observed only in dogs, Tasmanian devils, and some marine bivalves. Researchers identified the cancer in fish from lakes in Quebec and the U.S., with specific locations including the St. Lawrence River and lakes in the northeastern United States. The discovery is significant because it suggests that transmissible cancers may be more common in the animal kingdom than previously thought, potentially affecting broader ecosystems. The study's authors note that the cancer does not appear to pose a risk to humans, but it could impact fish populations and the health of freshwater environments. Next steps involve further research to understand how the cancer spreads and whether it could affect other species. The findings also raise questions about the role of environmental factors, such as pollution, in facilitating the emergence of such diseases.