Lake Memphremagog Catfish Carry Transmissible Cancer, Study Finds

A Nature study confirms brown bullhead catfish in Lake Memphremagog host a transmissible cancer in which cancer cells spread between fish like a parasite. It’s only the fourth documented case of a contagious cancer in the animal kingdom. The tumors appear as black lesions; surveys from 2014–2017 found about 25–33% of the lake’s brown bullhead infected. Transmission mode is not yet known (spawn-related spread suspected), but researchers say it does not appear to pass to other species and poses no threat to human health. Further work is needed to understand spread and population impact.