If this is the fish you are calling a warmouth, its what we call a goggle-eye. Looks like a bream with the mouth of a bass or crappie.
I don't think it would be much of a predator of bream. I would recomend throwing a few catfish in the pond to eat the smaller bream.
This picture is originally posted by nralover on this thread. http://www.crappie.com/gr8vb3/showth...ghlight=goggle