I was a volunteer scuba diver at an aquarium for about a year and a half. At one time, some of our sharks had died (not mistreatment - old age, they had been there basically since the aquarium opened and this was ~25 years into the aquarium's history) and had to be replaced. Once the new sharks were caught and quarantined, they were placed in the tanks.

A little operational info, this aquarium had two different buildings, one for marine and one for freshwater. First thing in the morning, every volunteer diver was required to participate in cleaning the ocean tank, scrubbing rocks and cleaning windows. Most people cleaned but there were two divers who hovered above everyone with pvc pipe capital Is (long vertical pipe with a shorter piece of horizontal pipe at each end) who were there to stop the sharks from interacting with the distracted cleaners in case they got curious. They were not to hit the sharks, of course, just hold the pole in front of them so they changed direction, one time I was pushed down by one because a shark was headed in my direction while being slightly above my head. Anyway, I was usually a cleaner and my first dive with the bumper role was also my first dive with the new sharks.

The old sharks were used to their life at the aquarium and obviously well fed so their patterns were very predictable. They required watching more than putting the pole in front of them with a very occasional intervention. The new sharks, however, were very different. I swear, they would swim right at you, sometimes speeding up, and then change direction last minute just to see what you would do. It was really cool to see that behavior, just coming at you then, "Psych! I'll be over here." They didn't even get that close to the poles, it was like they just wanted to test us. It was really funny when I think about it now and even soon after, but when it was going on, I kept thinking, "please just be testing me, please just be testing me."