Why do some bass that I catch have black spots?

Related: For an example of unusually dark pigmentation across much of a fish, see our page on melanistic black largemouth bass.

That is a question that many anglers have asked themselves at least once or twice.

So what causes these dark blotches or spots on the skin of bass? Well, nobody really knows exactly but it’s called melanosis (melanin is a black pigment in the skin cells of fish) and the general consensus from longtime professional anglers and biologists is that it is from fish that have an increase in sun exposure and that often times it is a sign of a healthy bass in healthy waters. The spots could be caused by something that is genetic and the fish may be born with the splotches at birth. It could also be viral or related to environmental factors unique to that particular body of water.

Here are some ways people often try to describe these fish to others:

• Bass with oil spots
• Blotchy Bass
• Dalmatian largemouth bass
• Bass with black spots
• Camouflage bass

Is the bass infected?

No, the bass is not infected. When melanosis occurs it is just an increase in the melanin in the skin.

Can I get it?

No, the melanosis is not contractible from fish.