"They included skatole, a component of feces; trimethylamine, one of the essences of rotting fish; and several of the more pungent fatty acids that contribute to rancid human body odor, " Ed says.

Sometime fish eat the algae, but then they poop, and the nitrogen sinks to the bottom in the fish poop.

The vacuum sewage discharge system was utilized to collect fecal sewage in the design of toilet in the spot Viewing Fish at Green Pool of Tingtao Scenic Area of East Lake.