I used to work at a LFS and peeling eels off the floor is nothing new.
But I've got you all beat
There is a 180 gallon in a restaurant that was full of lava rock and bleached coral. The guy was willing to pay me to come out once a week and make the tank spotless. I tried to convince him of going another route, but he wanted the tank to remain the same, just cleaner. He was willing to spend money on me, just not the tank itself?
So anyway, there were 2 yellow tangs, couple of Monodactylus, some damsels and a lunare wrasse. When I would clean the tank the wrasse would just go hide in some of the rock. I would remove the white coral, put it in a trash can, fill it with water, add bleach, and wait for the coral to turn white again. Drain this water, set the coral outside on the sidewalk until dry, rinse it off, put it back in the tank.
Well one day nearing the end of the water change, while the bleached coral was airing out, a guy comes in and says "you know there is a fish out on the sidewalk?"
I go outside, and there was the wrasse laying beside the largest piece of coral in the tank. He had been submersed in freshwater, bleached for 10 minutes, and left outside for 10 minutes.
I threw him back in the tank and he was still pumping his gill, so I told the owner, when he dies, just pull him out, and I would bring him another one the next week.
The next week I bring another one, but there is already one swimming around in the tank. That one had lived. I questioned everyone who worked there who put the wrasse in there. They all said that it was the same one.