I have to make a comment here that some people may hate me for. I really could not be bothered to go to that length of detail to see why a fish died.
The way I look at my fish is this whilst they are alive I do my utmost best to care for them, to provide for them, to be the very best fish keeper I can.
Yet, on the same note if some of them die, it ceases to be a high priority for me to really care to much. After all they are just fish. Very much to be prized, enjoyed and loved while they are alive! Very much not to be treated as anything more than what they are when they die, surely missed but not much more than that after all they are just fish who in all reality would probably have eaten us if we were the right size to fit in their mouth.