Researchers reporting in Nature say melanoma in the brown bullhead catfish appears to be a newly identified transmissible cancer. The study points to a form of disease in which cancer cells themselves may move between animals, rather than each tumour developing separately inside each fish.
According to the report, the team used whole-genome sequencing to compare tumour samples with matched non-tumour tissues from the host fish. That analysis revealed genetic patterns consistent with a naturally occurring transmissible cancer, indicating the tumour cells share a distinct origin that is separate from the normal cells of the individual animals carrying them.
The finding is important because transmissible cancers are considered highly unusual in the natural world. By showing that brown bullhead catfish melanoma fits this category, the research expands scientific understanding of how cancers can emerge, persist and spread in wildlife populations.
The work also highlights the value of genomic tools in studying animal disease. Comparing tumour DNA with host tissue helped researchers distinguish between ordinary cancers and a cancer lineage that may be passed from one fish to another, offering a new framework for investigating similar cases in aquatic species.
