Silver Dollars

[Avinitlarge]

We have noticed our silver dollars tail and fins go black on the edges from time to time. Anyone know why this is??

 

[ox5477]

Might have something to do with their overall mood. Many fish change color slightly when they change moods. I have no idea if this is right but seems like a good place to look at first. Could also be something to with their health.... maybe as nitrate rises then they feel like crap so their tips naturally turn black.....