Sri lanka’s mysterious “fish rain” reveals hidden environmental crisis as dams disrupt ancient migration patterns

When residents of northern Sri Lanka discovered freshwater snakehead fish scattered across their fields after an October thunderstorm, it might have seemed like a biblical miracle. But this latest example of “fish rain” – a phenomenon also documented in Honduras and Australia – reveals both fascinating natural science and a troubling environmental trend.

The fish don’t actually fall from heaven. According to Professor Asoka Deepananda from the University of Ruhuna, these aquatic creatures are lifted by waterspouts – swirling columns of air that create powerful vortexes over water bodies. “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 explains. The phenomenon is so real that he witnessed fish on rooftops near his own university during a 2012 incident in southern Sri Lanka.

While waterspouts explain some cases, scientists point to another cause behind Sri Lanka’s fish rain: the natural behavior of certain species during migration and breeding seasons. Some fish, like the climbing perch, have evolved special breathing mechanisms that allow them to survive brief periods out of water and even move between water bodies on land. However, this ancient biological behavior is increasingly disrupted by human development.

The growing number of dams across Sri Lanka now blocks traditional migration routes that fish have used for centuries. As these barriers fragment aquatic ecosystems, they may be inadvertently concentrating fish populations in smaller areas, making them more susceptible to being swept up by weather phenomena – turning an age-old natural process into a more frequent spectacle that highlights our changing environment.