Pic 1 is the bubbly, bruise-looking spots she had on her tail muscle. It was superficial, only; the muscle beneath was normal-looking. When I cut into the spots, I was able, with some effort, to express a little light-colored tissue with the consistency of fat tissue. I prepped a slide of it, so I can look at it under the microscope tomorrow morning.
Pic 2 is gall- and swimbladders on the left, yeah?, but the liver and its blotchy, yellowish appearance is what I was documenting.
Pic 3 is a view of her spine, through the swimming muscle that is caudal to the anal pore, so we are looking from the ventral side. Not sure what this hollowed-out area in the middle of her muscle is. Ruptured tumor? I would guess abscess, except there was no fluid: pus, blood or serous, inside that hollow. But the disorganized-looking tissue looks like an abscess does when it's been cleaned out. Or a tumor does when it outgrows itself.
That was the epicenter, though, of the swelling.
Pic 4 is the part that I'm not sure if it's normal or not; I wish I had snapped a pic before I cut into it. She seemed to have a channel or tube running the length of her dorsal spine. It was full of a gelatinous tissue that I've not encountered before. Over the muscular caudal end of her body, it looked bruised and had black mottling, although you could make a case that it matches the blotching of her skin, and I'm assuming the bruising was due to pressure from the edema.
The swelling was whole-body by the end, but there was no pocket of fluid of any kind, nor was her body cavity filled with fluid; it was diffused throughout all her tissue.
Her gut was empty (you can see a little in pic 2). I ran it as best as an amateur can, and didn't see anything unusual -- like parasites or obstruction.
Anything look like something anyone knows more about? I'd love to hear your thoughts! If not, well, this is what I found, and maybe it will be useful to someone one day.