Betta is sitting at the bottom of the tank not moving, but sometimes comes up to breath. I have tested the water, and it is fine. About a month ago she started sitting in the corner of the tank so I started testing the water and got everything balanced, what really seemed to sort her out that time was adding a tiny bit of aquarium salt to the water. She lives in a one gallon tank, no filter, yes heater, and has a marimo moss ball and snail, she is normally very active, but now she is acting sick again, but doesn’t LOOK sick other then her behavior.. I am very worried about her but out of ideas, please help!