Okay, so I think I figured out what killed my firs fish a few days ago. And it just about killed my other guy, but by sheer dumb luck I figured out what was going on and remedied the situation I had the National Geographic Cave Aquarium Plant in the tank with both fish. It seemed pretty sweet...

This is just a heads up from what I've noticed from my male betta, its that after I cleaned the glass of the tank, that when night time kicked in and no other light is on besides the tank light, it makes the glass inside the tank seem almost like a mirror, enough for even the betta to notice...