Hi LF. I heard one of your Bettas has severe fin rot due to 1ppm of ammonia in your tap water. If you're desperate, I suggest cutting his fins. But that's when you're ABSOLUTELY DESPERATE. Even experienced fish keepers find this hard but it might be the only way to save him. If you do, then after the cutting, place him in bottled water so there's no ammonia at all and do 100% changes daily, AQ Salt if desired etc.. The closer the fins are to the body, and that's where you cut, he might get hurt. It is a painful process if you cut close near the body so I wish you luck on whichever method you prefer.