Yes, filling that out will help a lot.. but it sounds as if it may be temp related.
Saying that the temp is always between 75-83 is a sign that you don't have a heater, and that the temp is fluxing which can be harmful to your fish. It will cause them stress and in some cases, a form of shock. Even though the temp is "within" the semi-appropriate temp range, it would be wise to get a heater and set it for 80*F so the water won't dip below that to reduce the fluxes going on the cold side.
Are they in the same tank? And if so, what sort of decorations are in there with them?
Can't really say more without filling out that form.. can't tell if that is enough of a water change or not. Sorry!