I got two pictus cats with my oscars, firemouths and angels in a tank similar to yours. I think you should be looking for cats that doesnt sit still and are able to escape quickly if necesary. But I have never experienced aggression towards my cats though. Iknow a guy who kept royal plecos with three fullgrown Oscars. They shared tank for a day or so before they were eaten.... ( Oscars ate pleco, not vice versa 
)
)