Mattski,
I have 10 in a tropical tank with platies, tetras, etc. My normal temperature is kept at 76 F to 78 F (24-26 C), and they all do fine. Very active fish. I've read an article in Aquarium USA that says they are most comfortable at 68 to 70 F, but that they will easily adapt to tropical temperatures (76 F to 78 F), and will thrive in temperatures as low as 60 F. Hope this helps a little.