Tank mates right now are an oscar, a common pleco and the odd ball gourami.
The gourami can go into any tank in my house. I can't see the pacu eating either the oscar or the pleco.
I also have in the tank about 2 dozen guppies. I have a guppy breeder going to make me live food for the oscar, but he doesn't seem to eat them. I add 6 or 8 guppies each week and the sheer quantity of guppies in that tank just keeps climbing. There are a LOT of floating plants in there, and I suspect the guppies are going to start breeding in the pacu tank. The gourami should solve that problem for me, I hope.
Ohh wait, there is also a tiger loach hiding in the rocks. I forget he is there as I don't see him too often. I doubt the pacu could catch him.