I have definitely seen that fish before but its name is not coming to me. Nice fish anyhow. What size tank are they in?
Looks like a Geophagus to me. Maybe Geophagus sp. "Altamira...
It also favors a Threadfin Acara (Acarichthys heckelii), but in the pictures I find, the fish aren't as irridescent looking on the fins, like your fish are.
If it is any type of Geophagus, its going to get pretty big. Most of them get atleast 6-8 inches I believe, and anything 8+ inches is going to be too large for your 46g (if thats the tank they are in) IMO.
not sure what it is but they look really neat.