On patrol, we (Advisors and VNs) would occasionaly have a "treat" of white, fatty fish of some kind. First time I stopped in a small hamlet though, I noticed the toilet built on stilts at the end of a rickety bamboo dock, extending out over a small fish pond. As people walked out the dock to the throne to do their business, the vibration caused the fish to gather under the hole. As the task was accomplished there were a series of swirls as the fish ( a large carp similar to Talapia) lined up for chow below the toilet. Recycling to perfection.

That's why I had to get dewormed once I got back to the States.

And oh, yes. That's also why I NEVER eat Talapia.