Anyone Have A Fish That's Looked Dirty? Ammonia?

[fishwatcher]

One of the 4 dwarf rainbows that I got a few days ago looks dirty. He has since I got him. He eats/swims/acts fine, he just looks dirty. I don't know how else to put it really. The lfs assured me they all were fine, but since he also sold me green spotted puffers as dwarf puffers, I'm not so sure about him anymore.
Any ideas why? Or if it's something that could spread?

 

[OohFeeshy]

If by dirty you mean covered in black marks, it's caused by ammonia, and sometimes heals, sometimes stays.

 

[fishwatcher]

yeah, it's the edges of his fins are black looking. There's no growth on them, or anything like that... gives the appearance of having been rolled in dirt.
I'm glad to hear it's nothing bad like a disease. I'd hate for my others to get sick, too.
Thanks!

 

[WILDER]

So it's definately black not brown, black patches like has been said are ammonia burns that are now healing.

 

[fishwatcher]

yep, not brown. it almost is like the edges of his scales have a dark gray/black edge on them, only it's not like a definitive line... if that makes any sense. LOL It looks smooth from the sides/top/back. Just dirty looking.
So you think he's safe to have with the others?