This is what I would do if I had that tank: Set up a centerpiece consisting of large rocks, driftwood, an a few plants right in the center of the tank, right up through the surface; get a bunch of schooling fish that maxes out at about the 12" range; this gives the fish a perception that they are swimming in an endless waterway and they'll keep moving constantly. I would personally do something like clown loaches, silver dollars, and a large school of tiger barbs or tetras

