Black Spots? Advice Please

The spots on the dorsal fin in the photos don't look like anything wrong to me.

There is a thread on another forum concerning the ID of 2 adopted silver dollars and the chap replying on that thread - a fish expert - stated that there are 28 species assigned to the Metynnis genus but there are only 14 actual species, some of the 28 are the same species as others. But that still leaves 14 any of which could be sold as silver dollars.

Looking at your photos I would suggest that perhaps you have a species which has black spots in the dorsal fins.


As for your guppies, there is a huge array of different colours and patterns, and a lot of them have black spots in various fins. Do you have any photos of your guppies? And yes I do realise how hard it is photographing fast moving fish 

I'm not convinced my guppies have it,  and none of my other fish have it... I'll keep an eye on them