Try apistogrammas, they are very peaceful, though you may run into problems if you decide to get a pair and they spawn, becasue they can be more territorial, escpecialy if you don't have good territories set up for them.
I have actually tried to remove some of my guppy fry by feeding them to my apistos, but the apistos didn't eat them and I ended up with full size guppys in the tank after a while. So you should be fine with most apistos.
I am not so sure about them and shrimp, they don't bother amanos for me, but I haven't kept them with other types of shrimp because I think they would eat them, I am not sure though.