How aggressive are Silvers?

[cichlid savage]

My silver approx 15" just killed my CKF. I am trying to get the 100 gal ready to move him (alone for now). How aggressive can silvers get?
I want to put a cpl of rays in with him but I dont want to waste a cpl hundred bucks for him to kill them.

 

[rallysman]

Normally (and if they have enough room) they wont mess with anything that wont fit in their mouth.

 

[Bderick67]

My silvers only get aggressive at feeding time. Every once and a while the smaller will nip the larger one to move him outof his way, but other then that they are fairly placid. Never any aggression towards all the gouramis in the tank.

 

[ethnics]

only agression i usually see, is towards other silvers unless there's like a lot or u get lucky. or very small fish that can fit in there mouths. usually very calm