I'm really surprised at how hardy these tiny fish have been for me... they are the smallest fish in the tank, but seem to be thriving in the conditions of my Hillstream tank, even though each has looked emaciated when they arrived... the bigger fish in this tank leave them alone, and they roam around the tank freely... the 1st one I got, is 3-4 times bigger than when it arrived... they seem very independent, though I think I had read they should be in groups... I see all 3 of them this morning, though they are spread out over the whole tank..