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.

 

[mrrobxc]

You can see it on his mouth.

 

[Pomatomus]

You can't rule out disease because just one fish is affected. It could be difficult to transmit or perhaps the affected fish's immune system was compromised by stress. Dropsy is often only observed in one individual in the tank. I'm not sure what it is though! Maybe it's just his genes.

 

[Woefulrelic]

Can't help but here's a bump

 

[Izard-industries]

I had about 15 columbian tetras with a similar pattern. All died within about 2 weeks of getting it. All within about 2 months of each other. I had one left and he has made it about a year longer than the rest but now is showing signs the same as before.

Think I need to clean the back of my tank! Bit dirty!!

 

[k13k07]

I had two black tetras do that, but theirs was on the mouth and body. Nobody could tell me what it was and I was unable to find anything about it. I had no idea how old they were (they were given to me) but they died a couple months after getting the spots

 

[Izard-industries]

Maybe it's like age spots? Fish wrinkles!??