Contagious cancer found spreading among catfish in North American lake

Researchers have documented a new case of contagious cancer, a melanoma spreading among brown bullhead catfish in Lake Memphremagog, which straddles Quebec in Canada and Vermont in the US. Cancers normally arise from a patient's own cells, and only three natural transmissible animal cancers were known before. Scientists say the finding could offer clues to preventing organ transplant rejection in humans.