Caudal fin is the tail fin. The whole tail was gone (chunk of flesh missing/exposed)? Or just the fin rays gone?
Anything (fish, crayfish, etc) that could have ripped/cut it off?
Look weak swimming on got caught on the filter intake or something like that?
Or does it look infected, like rotting flesh or fungal growth?
Never heard of organs being expelled out, so I doubt the object was a organ. I haven't seen/heard of everything though! (actually may have heard of one or two cases, but extremely rare and none of any object this large). Dissecting the object may have shown what the center of it looked like to better ID it.
No parasite I know of would tear down a tail fin overnight.
Rotting flesh from a disease would normally progress fairly slowly.
So I am thinking something larger would have caused the tail damage.
Besides the tail, how's the fish doing? Eating, still colorful and active? Any other signs of deteriorating health?