Silver Dollars slapping their tails together

Not sure, but my guess would be "Slap me some fin buddy!"

I haven't research silver dollar breeding habits, but if it is just 2 doing it, and they swim to different areas and carry on, they could be breeding.
 
They are showing aggression to each other. If they dont have enough room, they will fight for dominance by smashing their bodies together, and giving "high fins." What size tank are they in and how big are they?
 
This thread just makes me smile.....:werd:
 
Males still fight for dominance any way, so they are probably all males, they are one of the only characins that do that really. Because tinfoil barbs are literally stupid, they dont know that they arent silver dollars, and join in. Ive seen similar cases where bala sharks join in aswell.
 
AquariaCentral.com