Behind Sri Lanka’s ‘fish rain’ lies a web of migrations now blocked by rising dams

COLOMBO — From time to time, curious tales of “fish rain” grab media attention: fish seemingly fall from the sky, far from any bodies of water, following heavy downpours. The most recent incident occurred in northern Sri Lanka in October, after a thunderstorm, when residents discovered snakehead fish, a freshwater species, scattered across rain-soaked fields.

Similar incidents have also been recorded in Honduras and Australia. But the fish don’t actually come from the sky. They come from lakes or lagoons, and are sucked up into the air by swirling columns of air known as waterspouts, which create a vortex effect, says Asoka Deepananda, a professor of fisheries biology at the University of Ruhuna.

Once airborne, they’re carried overland, eventually dropping as the vortex weakens, he says. “This can happen especially after heavy rain following a long dry spell, when fish are concentrated in small water holes and can easily be lifted in numbers,” Deepananda tells Mongabay.

He points to one such episode in southern Sri Lanka in 2012, when fish were found on rooftops near his university. “That incident clearly indicated that fish rain can occur. Reports from other countries describe frogs and other aquatic species falling from the sky as well, which are strange, but scientifically known events,” he says.

Some fish like this climbing perch have specially adapted breathing mechanisms that allow them to survive outside water. Image courtesy of Madusanka Mihiran. ‘Natural biological behavior’ Not every incident of fish rain can be explained this way, says Rohan...This article was originally published on Mongabay