Harish Pullanoor spent his weekends in the late 1980s tramping around the marshes and ponds of Yemalur, an area then on the eastern edge of the Indian metropolis of Bengaluru, where his cousins would join him catching small freshwater fish.

In the 1990s, Bengaluru, once a genteel city of gardens, lakes and a cool climate, rapidly became India's answer to Silicon Valley, attracting millions of workers and the regional headquarters of some of the world's biggest IT companies.

The untrammeled expansion came at a price.