I vote for the regurgitation too. She was stressed in too small a tank, feeling trapped all the time.
Have you been measuring the water for the basic ammonia, nitrite, and nitrate, pH, and temp? If no - huge mistake. Any one of these parameters could kill if not in check. If yes and all those are within the norm, then it is the stress of too small a home, followed by puking, followed by quick death - in such a small tank/water volume, the stomach acid from the puking alone could have been enough to kill, not to mention paralyzing the filter/pump/BB/oxygen supply, etc.
I like how receptive and conscientious you are and you know where you went wrong. I commend you for this greatly. I've learned from many similar painful mistakes. But yes, you've kept a Clydesdale in a pony barn. No big surprise in the outcome. I am surprised there apparently was no violent thrashing and darting and attempts to knock the cover off, as you didn't mention those. It is not a must but an often observed behavior of RTCs in too small tanks.
Have you been measuring the water for the basic ammonia, nitrite, and nitrate, pH, and temp? If no - huge mistake. Any one of these parameters could kill if not in check. If yes and all those are within the norm, then it is the stress of too small a home, followed by puking, followed by quick death - in such a small tank/water volume, the stomach acid from the puking alone could have been enough to kill, not to mention paralyzing the filter/pump/BB/oxygen supply, etc.
I like how receptive and conscientious you are and you know where you went wrong. I commend you for this greatly. I've learned from many similar painful mistakes. But yes, you've kept a Clydesdale in a pony barn. No big surprise in the outcome. I am surprised there apparently was no violent thrashing and darting and attempts to knock the cover off, as you didn't mention those. It is not a must but an often observed behavior of RTCs in too small tanks.