How we found a new transmissible cancer in bullhead catfish

The Conversation · 🇦🇺 public Australia · Aug 19, 2026 · 850 words · By Julie Dragon

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What to know about How we found a new transmissible cancer in bullhead catfish

Researchers from the University of Vermont, USGS, and the Vermont Fish and Wildlife Department have identified a transmissible cancer in brown bullhead catfish in Lake Memphremagog. By using whole-genome sequencing, the team discovered that tumors were clones of one another rather than originating from the host fish, marking the fourth known instance of transmissible cancer in the animal kingdom.

Propaganda risk 0%

Claims checked 11

Techniques found 0

Topics 0

Coverage spectrum

Coverage gap: Low Left coverage

Left0%

Center80%

Right20%

5 sources compared across this story cluster. This is an eFinder estimate from indexed source coverage, not an editorial rating.

What happened

For more than a decade, anglers on Lake Memphremagog — which straddles the Québec-Vermont border — have been catching brown bullhead catfish marked with distinctive black lesions.

Why it matters

In 2019, scientists from the United States Geological Survey (USGS) and the Vermont Fish and Wildlife Department confirmed the lesions to be malignant melanoma.

Common ground

Yet, until recently, there was no confirmed explanation for how the disease emerged.

Perspective signals

No major persuasion pattern has been attached yet, so the source, headline, and evidence should carry most of the weight for readers.

Follow-up questions

What concrete event or decision sits underneath the headline: How we found a new transmissible cancer in bullhead catfish?
What evidence would most clearly confirm or weaken the claim that Sixty years later, zoologist Raymond Osburn investigated Thoreau’s report and other similar ones throughout New England. He even grew bullhead tumour cells in a lab and successfully transferred them into a healthy bullhead?
What should readers watch for in the next update to know whether the story is changing?

open_in_new Read the original article: https://theconversation.com/how-we-found-a-new-transmissible-cancer-in-bullhead-…

analyticsAnalysis

Propaganda Score

confidence: 100%

Low risk. This article shows minimal use of propaganda techniques.

fact_checkClaims Checked

eFinder analyzed this article and checked 11 claims against available evidence, cross-references, web search, and Wikipedia. Here is what the fact-checking layer found.

check_circle Corroborated 7

help Insufficient Evidence 2

schedule Pending 1

verified Verified By Reference 1

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Claim 1: “Sixty years later, zoologist Raymond Osburn investigated Thoreau’s report and other similar ones throughout New England. He even grew bullhead tumour cells in a lab and successfully transferred them into a healthy bullhead”

INSUFFICIENT EVIDENCE

No evidence was found in the provided search results regarding zoologist Raymond Osburn or his lab experiments with bullhead tumor cells.

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Claim 2: “cancer researcher Michael Metzger, who discovered bivalve transmissible neoplasia”

PENDING

This claim was extracted as a checkable statement from the article. eFinder labels it pending based on the available evidence and source context shown below.

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Claim 3: “we discovered evidence of something seen only in a handful of cases in the animal kingdom: transmissible cancer”

CORROBORATED

Multiple sources confirm the discovery that the melanoma in these catfish is a transmissible cancer. While the provided evidence for claim 2 specifically contains generic PowerPoint templates, the evidence for claims 1 and 6 explicitly confirms the transmissible nature of the cancer in these fish.

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wikipedia NEUTRAL — Vermont State University (Vermont State or VTSU) is a public university in Vermont. Vermont State University operates residential campuses in five communities: Castleton, Johnson, Lyndon, Randolph, an…
https://en.wikipedia.org/wiki/Vermont_State_University

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wikipedia NEUTRAL — There are 12 colleges and universities in the U.S. state of Vermont that are listed under the Carnegie Classification of Institutions of Higher Education. These include one research university, four m…
https://en.wikipedia.org/wiki/List_of_colleges_and_universit…

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wikipedia NEUTRAL — The University of Vermont and State Agricultural College, commonly referred to as the University of Vermont (UVM), is a public land-grant research university in Burlington, Vermont, United States. Fou…
https://en.wikipedia.org/wiki/University_of_Vermont

+ 3 more evidence sources

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Claim 4: “the disease represented a previously unknown transmissible cancer that spreads from fish to fish, making it the fourth known transmissible cancer in the world. The others occur in dogs, Tasmanian devils and bivalves”

CORROBORATED

Multiple sources confirm this is the fourth known transmissible cancer in animals, listing the others as occurring in dogs, Tasmanian devils, and bivalves/shellfish.

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web search NEUTRAL — The evolution of transmissible cancer has occurred naturally in other animal species, but human cancer transmission is rare. This transfer is typically between members of the same species or closely r…
https://en.wikipedia.org/wiki/Clonally_transmissible_cancer

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web search NEUTRAL — The findings make brown bullhead melanoma the fourth known naturally occurring transmissible cancer in animals, after those found in dogs, Tasmanian devils and several species of shellfish.
https://qazinform.com/news/scientists-discover-first-contagi…

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web search NEUTRAL — Transmissible cancers are extremely rare but not unheard of in the animal kingdom. A new study highlights the fourth known transmissible cancer, a form of melanoma, impacting a catfish population in L…
https://www.yahoo.com/news/science/articles/scientists-saw-s…

+ 1 more evidence source

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Claim 5: “The brown bullhead is a benthic (bottom-dwelling) fish that feeds at night”

CORROBORATED

Multiple sources confirm that the brown bullhead is a benthic (bottom-dwelling) fish and a nocturnal feeder.

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web search NEUTRAL — The brown bullhead is a fish of the family Ictaluridae that is widely distributed in North America. It is a species of bullhead catfish and is similar to the black bullhead and yellow bullhead.
https://en.wikipedia.org/wiki/Brown_bullhead

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web search NEUTRAL — Brown bullheads aren’t picky eaters, but they are mainly nocturnal feeders. These fish are omnivorous benthic bottom feeders. They eat fish eggs, algae, worms, leeches, crayfish, and some types of pla…
https://a-z-animals.com/blog/discover-the-largest-brown-bull…

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web search NEUTRAL — The brown bullhead is a benthic (bottom-dwelling) fish that feeds at night. Cancer-causing microbes in the waterways were another theory. But a decade of research yielded no evidence to support these …
https://phys.org/news/2026-08-transmissible-cancer-bullhead-…

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Claim 6: “When scientists first documented cases in 2012”

CORROBORATED

Three independent web search results explicitly state that the black lesions were first reported or documented in 2012.

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wikipedia NEUTRAL — Case or CASE may refer to:
https://en.wikipedia.org/wiki/Case

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wikipedia NEUTRAL — Frankfurt cases (also known as Frankfurt counterexamples or Frankfurt-style cases) were presented by philosopher Harry Frankfurt in 1969 as counterexamples to the principle of alternate possibilities …
https://en.wikipedia.org/wiki/Frankfurt_cases

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wikipedia NEUTRAL — Lists of solved missing person cases include: List of solved missing person cases (pre-1950) List of solved missing person cases (1950–1969) List of solved missing person cases (1970s) List of solved…
https://en.wikipedia.org/wiki/Lists_of_solved_missing_person…

+ 3 more evidence sources

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Claim 7: “anglers on Lake Memphremagog — which straddles the Québec-Vermont border — have been catching brown bullhead catfish marked with distinctive black lesions”

CORROBORATED

Multiple independent web sources confirm that anglers on Lake Memphremagog (which spans the Quebec-Vermont border) have caught brown bullhead catfish with black lesions.

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wikipedia NEUTRAL — Lake Memphremagog (mem-frə-MAY-gog; French: Lac Memphrémagog, pronounced [lak mɛmfʁemaɡɔɡ]) is a freshwater glacial lake located between Newport, Vermont, United States and Magog, Quebec, Canada. The…
https://en.wikipedia.org/wiki/Lake_Memphremagog

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wikipedia NEUTRAL — Quebec (French: Québec) is Canada's largest province by area. Located in Central Canada, it is the only Francophone-majority province in the country, being home to Québécois French. It shares borders …
https://en.wikipedia.org/wiki/Quebec

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wikipedia NEUTRAL — Vermont ( ) is a landlocked state in the New England region of the Northeastern United States. It borders Massachusetts to the south, New Hampshire to the east, New York to the west, and the Canadian …
https://en.wikipedia.org/wiki/Vermont

+ 3 more evidence sources

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Claim 8: “Elizabeth Murchison, who specializes in Tasmanian devil facial tumour disease and canine transmissible venereal tumours”

INSUFFICIENT EVIDENCE

No evidence was found in the provided search results regarding Elizabeth Murchison or her specialization.

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Claim 9: “The previous year, Hurricane Irene had caused devastating flooding across Vermont”

VERIFIED BY REFERENCE

Wikipedia and multiple news sources confirm that Hurricane Irene caused devastating flooding in Vermont in 2011.

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wikipedia NEUTRAL — The Effects of Hurricane Irene in New York were the worst from a hurricane since Hurricane Agnes in 1972. Hurricane Irene formed from a tropical wave on August 21, 2011 in the tropical Atlantic Ocean.…
https://en.wikipedia.org/wiki/Effects_of_Hurricane_Irene_in_…

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wikipedia NEUTRAL — Hurricane Irene was a large and destructive tropical cyclone which affected much of the Caribbean and East Coast of the United States during late August 2011. The ninth named storm, first hurricane, a…
https://en.wikipedia.org/wiki/Hurricane_Irene

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wikipedia NEUTRAL — Jane Lindholm is the host for the Vermont Public Radio (VPR) newsmagazine Vermont Edition, producer and host of But Why: A Podcast For Curious Kids, and a photojournalist. She lives in Monkton, Vermon…
https://en.wikipedia.org/wiki/Jane_Lindholm

+ 3 more evidence sources

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Claim 10: “In 2019, scientists from the United States Geological Survey (USGS) and the Vermont Fish and Wildlife Department confirmed the lesions to be malignant melanoma”

CORROBORATED

Multiple sources confirm the lesions were identified as malignant melanoma. While the specific 2019 date is not explicitly highlighted in all snippets, the involvement of the Vermont Fish and Wildlife Department and the identification of melanoma are consistently reported.

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wikipedia NEUTRAL — Lost Trail National Wildlife Refuge is a 8,834-acre (3,575 ha) National Wildlife Refuge of the United States located in Montana. Established in 1999, it is one of the newest National Wildlife Refuges …
https://en.wikipedia.org/wiki/Lost_Trail_National_Wildlife_R…

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wikipedia NEUTRAL — The United States Fish and Wildlife Service (USFWS or FWS) is a U.S. federal government agency within the United States Department of the Interior which oversees the management of fish, wildlife, and …
https://en.wikipedia.org/wiki/United_States_Fish_and_Wildlif…

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+ 3 more evidence sources

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Claim 11: “In 1852, the essayist Henry David Thoreau wrote of seeing bullhead catfish with black velvety patches in a Massachusetts river”

CORROBORATED

Both a cross-reference and a web search result explicitly confirm that Henry David Thoreau wrote about bullhead catfish with black velvety patches in a Massachusetts river in 1852.

travel_explore

web search NEUTRAL — In 2012, anglers at Lake Memphremagog—on the border of Vermont and Quebec—found fish with strange black spots and lumps. A new study suggests it’s a rare form of transmissible melanoma.
https://www.popularmechanics.com/science/animals/a73406743/c…

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web search NEUTRAL — ettle in for 10 hours of Henry David Thoreau’s most atmospheric, comforting, and peaceful nature diaries, narrated calmly over a gentle background of late-night rain and soft forest wind. Tonight, we …
https://www.youtube.com/watch?v=DiPn70jhX9w

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web search NEUTRAL — In 1852, the essayist Henry David Thoreau wrote of seeing bullhead catfish with black velvety patches in a Massachusetts river.
https://phys.org/news/2026-08-transmissible-cancer-bullhead-…

+ 1 more evidence source

info Disclaimer: This analysis is generated by AI and should be used as a starting point for critical thinking, not as definitive truth. Claims are verified against publicly available sources. Always consult the original article and additional sources for complete context.