These little guys are so curious and active that I want to make sure they are entertained. Any suggestions on things to add or tank scape that will be optimal for these little cuties? FYI: 8 zebras, 20g high, no tankmates, fake plants, HOB, airstone. Fully cycled (0/0/10 today). I may add 4 or 6 more if you guys think they will fit. ETA The tank has a black background, black sand, a pile of larger smooth river rocks, and a tunnel that they go through sometimes.