A genetic investigation released on July 22, 2026, reports that melanoma skin‑cancer tumors can be transmitted between catfish populations in Quebec and the northeastern United States. The research, based on DNA analysis of affected fish, indicates that the cancer cells are capable of moving from one individual to another, a behavior previously unrecorded for melanoma in this species.
Melanoma in humans and most animals is classified as a non‑contagious disease, arising from mutations within a single organism’s cells. However, the scientific literature includes a small number of transmissible cancers that have been documented in wildlife, such as the facial tumor disease in Tasmanian devils and the canine transmissible venereal tumor. The new findings add catfish melanoma to this limited list of cancers that can spread through direct cell transfer.
The study’s authors emphasize that the discovery does not imply an immediate threat to human health, but it does raise questions about the mechanisms that allow melanoma cells to survive outside their original host and establish new tumors in another fish. The researchers suggest that further work is needed to determine how the disease spreads in natural waterways, whether through direct contact, waterborne cells, or other vectors.
Officials in Quebec and the neighboring U.S. states have been alerted to the presence of this transmissible form of melanoma. Monitoring programs may be adjusted to track the occurrence of the disease in wild and farmed catfish populations. The findings also provide a new model for studying cancer transmission, potentially offering insights that could inform broader cancer research.
The report concludes that while melanoma remains largely non‑contagious across most species, the catfish cases demonstrate an exception that warrants continued scientific attention and surveillance in affected regions.