What are these black marks?

[dianas]

Some of my fish have these black marks on them. None are acting sick. All parameters are normal and have been this way since I set up the tank almost 2 months ago.
Ammonia 0
Nitrite 0
Nitrate 10
PH 8.2
GH 11
KH 15
Temp 80degrees F

The fish have been treated twice for parasites they had when I received them. Any idea what these black marks are, if anything? Thanks.

This Neon Violet Ungi has some streaks on his side and one on his fin.

 

[bigspizz]

I am not familiar with that particular species, but in a lot of the CA/SA's I keep, these black marks show from time to time, when the fish has been moved, or stressed for whatever reason. Nothing to worry about if that is the case. Have you noticed any chasing?

 

[dianas]

No chasing or agression in the entire tank. Most of these guys came from a fish farm where they were in ponds. They already had these marks so maybe it is from stress. Just wanted to double check if anyone else has ever seen marks like these! Thanks for replying. . .puts my mind to ease.