I used to like to shoot at our local zoo and I figured out that if I came on days when there would be no other visitors...like during torrential rainfalls...I'd have the place all to myself. All I had to do was cover my gear and myself with a big poncho, then go shoot at all the indoor exhibits. One of the first times I did this, I came walking up to the ticket window in a downpour and the lady said, "You've GOT to be kidding me!"
On one such day, I was shooting at a massive saltwater aquarium inside the aquatic exhibit and using a flash to help freeze the motion of the fish. I'd been watching through my viewfinder and shooting whatever happened in front of my lens when I began to notice that there were hardly any fish coming by. I pulled down my camera, looked around the aquarium, and saw that all the fish were gone! Or so I thought. That's when I spotted them up near the surface, floundering on their sides like they were about to die. My first thought was, "Oh no! I've killed $20,000 worth of fish!"
Luckily though, it appeared that my constant use of a flash must have simply disoriented them because they all went back to their normal routines once I stopped shooting.
It sure scared the wits out of me though.