black spot on silver dollar

[floridalove]

i have 3 silver dollars about 3inches long in a 55 gallon tank, tank got 7 zebras 1 pleco, fully cycled. turned the light on seen this black spot on one of the silver dollars kinda where its heart should be? is this a concern as it went away after the light was on for 5 min

thanks

 

[BandE]

We have the same thing happening to us, floridalove-you're not alone. It only happens once in a while, and the fish doesn't appear sick or stressed, and water params are normal/good. Anyone have any ideas?

 

[KateRedDevil]

I know what you both mean.... 2 of my SD's have this black mark on them that seems to depend on the lighting.........strange!