I like
L3CTR0N
have had and still have a ctenopoma acutirostre with my polys including rope fish. No issues between the two. I wouldn't put very small polys with mine now as it's a good 6" easy.
I see you've decided not to go this route because of tank space. Thats a good decision. Besides looking at tank size for fish you also need to look at how many or should I say how few animals your tank size can house without issue. Many people things go into this aggression, waste management, time spent cleaning and so on.