FW Angelfish Help Needed

I purchased an fully grown (6") angel today and added it to my 55g
tank. Within an hour, another smaller angel (4"), had shredded my new
angel. The new angel didn't even fight back. I have a third angel
(3") that was fine and didn't do a thing. In a panic, I put the
agressive angel in a 5g bucket with an aerator and heater. The new
angel looks like it is doing better, but we'll see if it survives the
night. What should I do? Thanks in advance. -Matt

55g setup: (running approx 1 year)
fake plants, moderately planted
3 plastic caves/tree stump

2 Clown Loaches (3" each)
1 cory
1 blue ram
3 angelfish (3", 4", and 6" including the new one)
1 pleco (5-6")
6 white clouds