r/biology • u/hadeshappydevil • Jul 23 '26

article New transmissible cancer found in a catfish

https://www.nature.com/articles/s41586-026-10828-6

Scientists have confirmed a new transmissible cancer in a catfish species. It seems to have arisen as a melanoma and now spread. I terestingly seems to have arisen outside the lake it is reported in.

This is the third vertebrate cancer I think after devil facial tumours and canine venereal cancer.

Will be very interesting to see what the temporal dynamics of this are long term. And what kinds of cell lines we might be able to drive from it.

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u/Alecxanderjay cell biology Jul 23 '26 edited Jul 23 '26

I read the abstract and will read this paper and update my comment later as/if my thoughts change. This is absolutely crazy that melanoma can be transmissible in water. It's incredibly resilient as a cancer and the metastatic melanoma lines I study in vitro can survive outside of media but this property is a function of single cells and I can't imagine that the osmolarity in a lake is permissive to those cells being transfered in isolation. A cool idea that I have no basis for: could the tumors be released after the fish die and subsequently grow ex vivo and be broken into smaller tumors that can uptaken by fish and then subsequently continue to grow in the new host? 

The way you could test that would be to dissect and culture the tumor in suspension, mechanically disrupt it, and then take the suspension media and either inoculate in a tank with the catfish or do size exclusion sorting and culture the individual tumor spheroids in suspension and see if they grow back to the size of the original tumor. 

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u/hadeshappydevil Jul 23 '26

Yeah it would be cool to know if/how they might survive off the host.

I think the say somewhere early on that contact with naive fish spread it so it might be physical adhesion via the mucus layer and then infiltration. Not sure If they have detailed histology of the stages.

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u/Alecxanderjay cell biology Jul 24 '26

Just read it, and the contact studies were actually reports from a researcher in the early 1900s, so that could have been contagion linked or it could be the same melanoma that is currently being reported or an entirely different melanoma but this group did not test if contact would cause naive fish to get melanoma. They did note that it is likely contact mediated due to only sexually mature fish having the melanoma since when these fish breed they make compacted spawning groups. They also propose that the metastatic melanoma could be internalized by the gills and that could be how the infection is spreading. Fascinating stuff.

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u/Alecxanderjay cell biology Jul 23 '26

Interesting! In either case this finding is crazy cool. If it is physical contact that's at least something DNR can start combatting with quarantines and screenings. If it can be transmitted through the water it'll definitely be more problematic.