Possible Disease In My Malawis

[Seed]

I have a well aged 120 US gallon tank with 10 african cichlids in it. I have kept African cichlids for years, and the only diseases I've ever seen were that white fungus and one episode of ich.

Tonight, I noticed my red zebra has some black smudge looking things around his mouth and along his ventral surface. They are of various sizes and look as though he somehow got himself dirty. He is not flashing or rubbing or behaving abnormally whatsoever. 7 of the other 9 fish display this same smudging look. Some of those have black streaks on the rays of their pectoral fins, one of them has some specks of it on his caudel peduncle.

Their behavior and apetite is normal. I have never encountered or heard of a black smudging disease.

I have noticed that the rock garden in the tank has become covered with black algae, and the fish feed on it frequently. Is it possible some of the pigment from this algae is rubbing off on them?

 

[Seed]

I think it was the black algae, it was all over them last night, and is gone now. Who knew fish could get dirty? I've never seen this before.

 

[HappyGeorge]

I'll have a pint of what you had last night

Bet you were relieved when you saw it gone

 

[Seed]

No kidding, it gave me a little bit of a scare.