What is this black pigmentation forming on skin?

[mrrobxc]

Hello all.

I have a pair of cincta and my big male has some black pigmentation that is forming on his skin. His behavior and appetite are fine and he has been slowly showing more of theze black blotches over time. The other fish don't have it which makes me rule out a disease.

Has anyone seen this before? Here are some pics. You can see it on his mouth.

 

[tanyaelec11]

have you changed its diet recently ?

 

[Stanzzzz7]

Could it be black spot?
I'm no expert on this but I had this some years ago on some angelfish.
Apparently it's a parasite brought in by new fish or snails.It get under the skin and forms black blotches. it is normally not that serious and can just die off.I think the parasites rely on the affected fish being eaten by a bird or other predator to continue its cycle.
Not 100% sure that's what it is but it may be worth looking more into.

 

[mrrobxc]

Thanks guys. It is harmless. Just can't figure out what it js. Thanks for the responses.

 

[jonclark96]

Looks like nerve damage to me. I've seen it in a couple of fish before. Nothing harmful, just that the skin turns black.