Dark Blotches On Bass

This is the first I’ve heard of this strange condition that can affect both smallmouth and largemouth bass. Little is known about the cause of these markings even though this condition was first observed in the 1980s. It is believed that this hyperpigmented melanosis may be a result of catch and release or is a natural defense mechanism against environmental contaminants. There isn’t a lot of conclusive evidence to support either theory 100 percent, but considering both pollutants and catch and release have increased over the years, you expect that these blotches would be extremely common by now.

Blotched smallmouth bass

    “The marks seem to eventually disappear, suggesting they may be part of a skin or slime repairing process. I’ve also noted that they seem to disappear faster from smaller adult bass. The largest fish seem to hold them for at least two years.”

More about the Bass Blotch Mystery at WMI

via OFNC

black-spotted-bass

According to the Tennessee Wildlife Resources Agency:

    “It is possible that this condition is genetic, viral, or related to some environmental factor unique to certain bodies of water that stimulates the increased production of melanin. This unusual pigmentation (melanosis) has been observed on bass within most Tennessee reservoirs and in other areas of the country for many years. The Fish Disease Diagnostics Laboratory at Auburn University is currently investigating the cause of hyperpigmented melanosis in Tennessee largemouth bass.”

Largemouth bass blotches

10 Comments
May 31, 2009 by Clive Mathias

Filed Under: Canada, Fishing, Freshwater Species, Largemouth Bass, News, Oddities, Smallmouth Bass, United States
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10 Comments on “Dark Blotches On Bass...”

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  • avatar Jonathon Marshall
    2 years, 8 months ago #

    It’s like reverse Vitiligo for fish.

  • avatar Mark
    2 years, 8 months ago #

    They had a lot of fish caught like this at the B.A.S.S. Tourney on guntersville.

  • avatar chris
    2 years, 8 months ago #

    Crikey! I’ve never seen anything like it! It doesn’t look good, does it?

  • avatar Woody
    2 years, 8 months ago #

    It’s one of those things that naturally appears in nature from time to time, it looks cool and makes a good picture!

  • avatar tyler bache
    1 year, 7 months ago #

    well we just cuaghtg one of these bass on longlake in ottertail county and we throw it back no picture anything damn

  • avatar Chris staton
    1 year, 7 months ago #

    I CAUGHT ONE OF THESE TODAY AT CHAIN  OF LAKES STATE PARK IN INDIANA. THE BLOTCH WAS ON TOP OF ITS HEAD BRHINDBEHIND ITSIT’S EYES AND WENT HALFWAY DOWN ITS DORSAL FIN.  

  • avatar bern fox
    1 year, 3 months ago #

    Caught/released a largemouth two weeks ago on Cedar Lake in Michigan with at least a half dozen of these black blotches; had a wide eye band making it look like a raccoon mask, and a false eye tail spot.
    Have fished this small lake for over 30 years, it has neither environmental adversities nor excessive fishing pressure, and have never seen/ caught this fish before:  very healthy 24″. 

  • avatar Mike
    9 months ago #

    I have been fishing a local pond for a number of years here in Kentucky and I have never seen bass with these black markings until this spring. However, in recent years this pond has become a goose haven. I think this melanosis may be a reaction to environmental contaminant…in this case…goose crap. The geese are the only change in the environment of this pond in the last 40 years.

  • avatar woody
    9 months ago #

    I rekon they’re all just ex-army…They have still got the camouflage!

  • avatar Lake Travis 1-22-12 blacks and whites, with pics (and a 36.8 pound bonus cat!) - Page 2
    2 weeks, 6 days ago #

    [...] 1,242 Never mind, I googled it Dark Blotches On Bass | Fishing Fury – A fishing blog with attitude! [...]

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