Cool Dale. How log did ya have to watch to see it?
(was it running for a long time)

(Shhhhh. It was running as a Screen Saver).
I have fish configured with 1 Volitans Lionfish (always) and 18 other fish (some random).
I'm rather sure that it had been running for only about a minute. I glanced up, saw that the clams were all closed, and then saw why. Watched the Lionfish move around for a bit over the clams, then swim away, and watched the clams re-open.
So, it was a fortuitous, accidental observation.
Perhaps could be easily duplicated if you were to populate the scene with 30 Lionfish?