As others have said, panfish make a great display. Great personality and social structure. Really anything up to chain pickerel would be a good fit. LMB, pike, musky, walleye and the like are too big. Personally I like American eels, bullhead, burbot, chain pickerel and panfish. Burbot can be harder to care for so unless you really want one I would leave it out. A small school or yellow perch can be a nice display too