I have a 12 gallon tank (Eclipse 12). Right now I have 5 neons, 2 dwarf gourami, and a spotted cory. The cories are the only fish that I have had any trouble keeping alive (aside from one neon that died immediately upon being introduced to the tank). I've had the tank going about 4 months. One cory died about a week after being introduced, when I was going through a rough cycle (Bio-Spira was not working as quickly as my reading had led me to expect, even though I used two packets from different sources). I replaced it. Another died maybe six weeks ago, for no apparent reason (the cycle was well over at that point). The one I have left looks to be doing well. The fact that I've read that they like to be in pairs makes me think I should get another. On the other hand, I'm just a little worried that as the fish grow a little I might not have room for anything else. Plus, of course, the fact that I've lost two might itself be a good reason not to get more.