Here are some pictures and a video of my Cuban pair, RTM pair, and Istlanum pair. Thses are all in the same tank with no dividers and no damages to each other. The Istlanums are currently guarding wigglers right next to where the Cubans recently layed their eggs, with no problems. Forgot to clean the glass but here they are, enjoy.
http://www.youtube.com/watch?v=8ggLDIbLxAk
http://www.youtube.com/watch?v=8ggLDIbLxAk