I was cutting up a mango, when I noticed some black threads inside.

What are those?

They are quite tough, brown-black, about an inch long (2.5 cm):

enter image description here

6 Answers 6


It's an indication that the fruit has started to rot.

When dark spots start appearing on the side of a mango, it's starting to rot. A mango can rot from the pit, the skin, or from the non-stem end. Any black fibers also indicate that the fruit has started to rot, and at that point, you need to toss it into the trash.

From Student's Vegetarian Cookbook For Dummies, page 301

Yes, the above is probably being overcautious in stating “any black fibers? → trash! It's from a “Dummies” book after all. I couldn't really find another good reference, but I'm sure you can make the distinction between a piece of fruit that has a small brown spot and one that's black and shriveled.

Still, the color of the fibers is a result of the late ripening/rotting process of the mango, rather than a result of an earlier stage in its growth, but having eaten this mango with the one, tiny black fiber shown in her picture, I don't really expect to read Mien's obituary on this site tomorrow.

  • 7
    I don't think it's rotten at that point. Overripe, sure. But, though I don't have a source off the top of my head, anecdotally, I've eaten tons of overripe mangos containing a few black fibers, and they tasted great and caused me no problems.
    – Cascabel
    May 30, 2012 at 18:03
  • 1
    Overripe mangoes are good for making mango ice-cream (the rotten sections need to be thrown off though).
    – Nav
    Jun 3, 2012 at 15:44
  • It appears that Mien survived at least 5 years after eating this mango.
    – Philipp
    Jun 26, 2022 at 18:27

Black streaks in mango. Please read the following articles from www.abc.net.au:

These articles identify the presence of well delineated black veins in otherwise good, fresh mango as a "disease" of the fruit. It turns out that this is caused by the mango trees lacking sufficient fertilizer.

  • 1
    Welcome to Seasoned Advice! Whilst this may theoretically answer the question, it would be preferable to include the essential parts of the answer here, and provide the link for reference. This time I added two sentences for you, but you may expand it too, to make your answer better.
    – rumtscho
    Jun 22, 2014 at 15:18
  • 1
    That's actually very good information, +1. Links go bad and not everyone likes to click them. To make this a stellar answer, take rumtscho's advice!
    – Jolenealaska
    Jun 22, 2014 at 15:32
  • 1
    Also sidesteps the question whether fruit so affected are inedible and/or harmful to eat... Nov 22, 2017 at 10:05
  • Recent evidence seems to indicate this is caused by bacteria infecting the fruit Jan 4, 2021 at 6:00

I believe some mangos do that in early stages of over-ripening (similar to how an avocado does that). I usually cut around them and keep eating.


It's not mango rot its actually a disease called Resin Canal which causes black fibers to appear in mangoes, there is no idea what causes the problem

  • Welcome to Seasoned Advice and thanks for taking the time to contribute an answer! Here is some help on how to write a good answer. Can you cite the source of your information?
    – Ess Kay
    Mar 22, 2019 at 14:00

Mango industry discovers highly infectious bacteria as cause of ugly veins of resin canal discolouration


  • I also would like to know why the best answer on here has the least points, in fact one minus (see below the answer of Raimond!)
    – Matteo
    May 30, 2019 at 11:59

Just to keep this thread accurate and current, the black fibers/veins in the picture are known as Resin Canal Disease, or RCD. Although unappealing, they are safe to eat, as described in this article: https://www.abc.net.au/news/rural/2019-03-19/resin-canal-discolouration-breakthrough-for-mango-industry/10912520

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