Melanosis (Black Spot, Blotchy Bass)


Commonly Infected Wildlife

Fish. Bass and catfish are commonly affected, but other species can also be affected.

Is This Animal Infected?

There are multiple causes of black spots in fish (flukes can cause black spots, for example). Melanosis is not an infection but an increase in the melanin in the skin.

It appears as small to large black patches of skin.

Can I Get It? 

No. Humans cannot contract melanosis from fish.

How Bad Can It Get?

Humans are not at risk for melanosis from fish.

Symptoms in Humans

None. People are not at risk for this type of melanosis.

Largemouth Bass with Melanosis
Largemouth bass with melanosis
Jim Negus

Protect Myself and Others

Consume fish fillets like any other, by properly cleaning, preparing, and cooking the fish to 145°F.

Safe for Pets?

Yes. There is no known health risk when fish are properly cooked.

What Causes It?

Melanosis is a genetic condition seen in mature fish following several years of sun exposure. A person’s risk of developing the similar-sounding (but unrelated) skin cancer melanoma is, however, increased with exposure to sun, which is why people are strongly encouraged to wear sunscreen.