About 10 years ago, in the middle of the night, I heard my single goldfish leave the tank, but I didn’t fully wake up and realize what had happened. So, in the morning, several hours after hearing the big splash, I found him (or her, not sure) dried up on the carpet behind the tank.
I picked him up and, in the process, peeled off the fins that were dried into the carpet and most of his tail. I was shocked when he twitched in my hand and—unfortunately—I screamed like a girl and dropped him from about waist height, thus adding insult and further injury to his already considerable existing wounds. I didn’t think he had a prayer, but I couldn’t bring myself to euthanize him, so I dropped him back into the tank. He was covered in hair and dust bunnies and sank straight to the bottom like a stone, made a lame attempt to ‘swim’ with only half of his fins and a stump for a tail. I reached in and picked off all the crap from the floor, then cradled him in my hands and drove him around in the tank to force a little water over his gills. Incredibly, after a couple minutes of this treatment he swam (if you can call it that) out of my hand and seemed fairly OK despite his ragged appearance and heavy breathing. I had to leave for an overnight trip, so I dropped some antibiotic into the tank and figured he’d be dead by the time I returned the next day. To my surprise, he was MUCH better the following day and was even nibbling at the Elodia floating in his tank. I kicked up his salt a notch and changed a bit of water. His fins eventually grew back, though he swam funny for a while and it was pretty embarrassing when new people saw him and invariably asked, “What the HELL happened to that poor fish!?” He lived for several years after that, although his ‘carpet’ side never quite looked right and he had a vertical line in his tail marking the place where the new growth started.
The lesson here is, keep a tight lid on your tanks or lower the water level to keep your fish out of jumping range. And you’d be surprised how HIGH some fish can jump!