I have a 3 mollies in a 15g tank. But one of them, the dalmation molly is always easily startled by movements and hides when I come close to tank. She hides when i feed them and comes back out to eat when I leave. I got them around Feb and she was never like this before, only noticed her like this a few weeks ago. I searched online for pregnant symptoms and found that these are behavior changes that can occur when a molly is pregnant though I'm not sure since she is the biggest out of the 3 and her stomach always looks big and then smaller after pooping but this time her stomach is a bit bigger and more noticeable especially around the sides where it looks like it is bulging and it almost looks box-like.