The first time I got a tankmate for Lilly, she was in a 5 1/2 tank with only one otto(it wasn't a good idea because they're suppose to be ina group of 3 minimum).
Ever since she is really hardy to other fish, well unless their sick. I guess she does such a thing that way the tank gets clean faster, to get rid of a sickness that could be contagious, or to reduce the amount of occupied space.
Since the white clouds don't have to take care of their sick brother anymore :(, they are way more active in the tank. Even though the white clouds know what lilly is capable of doing, they still feel safe and swim anywhere they want.
It is really nice having to hear from different pet owners that still are tough enough to place their fish in a bowl. My betta was in her bowl for 5 months.