I have a new fish that I'm floating in my 10 gallon as qt. He doesn't really seem sick, but I think that he is not doing so well in the cup. I do daily water changes, but I think he would be doing better with more space. I have a 1.5 gallon qt tank, but it is acrylic. The smallest heater I have is 7w and it heats up the qt tank WAY too much. But I have a .75 gallon glass vase. I'm testing the heater in it right now to see if it over heats, but so far so good. If the temp stays stable, should I try it, or just stick with floating the fish in a cup?