One of my big male Acei has an extremely concave belly, and has been pooping stringy white poop. He eats very well, knock on wood. Should I feed him Metronidazole food? A couple of other fish in the tank had the exact same symptoms, except not as skinny, a while back. They responded well to Metro and were completely better after a week. Should I worry about feeding him Metro? Any help would be appreciated.