Bottom-belly fish

Question
I have two bottom-belly fish living in a 5 gallon fish tank with a heater and filter. I have only had them for about a week but I have noticed lately that they look like they are seizing. The will stay in one spot and shake back and forth and then tip over onto their side like they cannot maintain their upright position. I am wondering if I can do anything to stop this?

Answer
Hello Christie,
Unfortunately there is no such thing as a bottom-belly fish. Perhaps you mean balloon belly molly or platy? In which case it is possible that the water quality is poor, and you need to do some more water changes. At least two 25% water changes a week, or one 40%.