Sudden death!

So I had this pearl gourami for quite a few months and suddenly without showing the slightest hint of poor health or stress she just up and died while I was at work. I fed her before I left. She ate as well as she always did. I came home to find her skeleton.

There are no issues at all with the water chemistry. The tankmates are all peaceful towards her - rasboras, SAEs and a female betta. No diseases or parasites in the tank. No new fish have been introduced in several months.

You all know me as someone who knows what he's doing so of course spare me the "did you do this, what was the condition of that" sort of stuff. haha

I've just never had a fish of this sort die so suddenly without a hint of distress beforehand. Naturally I'm accustomed to the sudden loss of small schooling fish and others like them. But to leave for work with a perfectly healthy and robust pearl gourami and come home nine hours later to a clean picked skeleton. Well, that's almost humorous.

I assume she would have to be infirmed enough to allow such opportunistic feeding. Keep in mind she was easily the alpha of the tank. No one in there would have had the nerve to just come over and start having a chunk of her unless they were sure she was weak enough to put up no fight.

It just seems odd to me that a centerpiece alpha fish in perfect health and who had eaten a good meal just hours before, could weaken so fast. I've never seen anything like it before. And I've been keeping fish for the better part of fifteen years.