My betta, whom I've had for over a year and a half, has been laying at the bottom of the tank for 2 days now with very labored breathing. I isolated him to a five gallon tank, but he isn't perking up. His coloring appears pale, as he is normally brilliant red, but other than that he doesn't have anything visibly wrong with him. He also isn't eating, not even his favorite bloodworm dinner. Is this just nature taking its course or is there something I can do for him?