I have been keeping five sexies in my 6G nano with my pair of Flaming Prawn Gobies. They are great little shrimps. I have never seen them eat and of the Zoanthids in the tank, but they will "host" on them and that keeps the zoas closed up some times. For the most part, they each have their own little space in the tank. One hosts in my ricordia, another in the frogspawn frag, one is in my scroll coral, one hangs out in a large purple mushroom and the last one hangs out on some zoas. They are usually in those spots but also move around the tank a good bit. They are really fun to watch. I have read that they do best in groups, and mine seem to be doing well.