Scott Young saw brown bullhead catfish with dark spots while fishing.

Young helped researcher Zoe Clarke collect fish to study a contagious cancer.

Clarke thinks the cancer in New Brunswick is the same as one found in Quebec.

Clarke asked, "How did this happen? Why is it here?"

They will study this for years.

Scientists found skin cancer on catfish in Lake Memphremagog from 2012 to 2018.

A study said the melanoma on catfish is contagious, a first for fish.

The researchers called it a "puzzling biological phenomenon".

This cancer is one of four known types that can spread between animals.

Dr. Julie Dragon said the tumors are copies of each other, not separate mutations.

Typical cancers have tumors similar to the host's DNA.

But these catfish tumors are different from the host's DNA.

The scientists want to know where the cancer started.

They don't think it started in Lake Memphremagog.

Clarke got a response from a student who saw lesions on catfish in New Brunswick.

Clarke is waiting for sample results from New Hampshire.

If the DNA matches, it will help solve the mystery.

Clarke will return to New Brunswick to sample more fish.

She might rent a camper van.

The researchers ask people to send photos of fish with lesions.

Studying the catfish could help researchers understand melanoma.

The catfish live in mud and feed at night, which is unusual.

The catfish could provide a model for studying melanoma.

Humans don't need to worry about catching cancer from catfish.

There's no evidence it can spread to humans.

Don't eat fish with obvious lesions.

Stick to the facts.

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