No way, RD would Kill the Jardini. Also, 55 is too small for both, even if they could co-exist in same tank. Agree with previous post, a recipe for disaster. But at least you are doing the right thing and getting advice. Good luck! Jardinis are so awesome!
I don't recommend you trying it. Those larger Central American cichlids are very aggressive and will eventually kill the jardini dispite jardinis being aggressive. A 55 gallon tank is way too small to house an arowana.