Fish deployed to contain dengue fever in Pakistan's Punjab
They eat the insects that would otherwise turn into mosquitoes and spread disease in Pakistan
The Guardian in Lahore
On one side of the battle are the countless swarms of mosquitoes that thrive in Pakistan's steamy summer months. On the other, vast quantities of hungry fish conscripted into a fight against a deadly virus that is reaching epidemic proportions.
Authorities battling the menace of dengue fever claim to have turned the tide against the mosquitoes that carry the disease with the help of 1.6 million fish released this year into pools, puddles, fountains and any other potential insect-breeding places they can find.
Punjab has waged an all-out campaign against dengue - a potentially lethal disease spread by mosquito bites - since a major outbreak in 2011 infected tens of thousands and killed more than 300 people.
Software designers were tasked to make smartphone apps to track outbreaks, the government cracked down hard on anyone who left old tyres in areas where they could collect rainwater and areas of stagnant water were doused with tonnes of noxious chemicals.
But it's the release of huge numbers of fish, even into water that soon evaporates, that many credit with helping to beat back the disease, which is now surging in other areas of the country.
"It's much better than chemicals that poison the environment," said Dr Mohammad Ayub, the director-general of Punjab's fisheries department. "And anyway, chemicals soon get washed away by the rain."
A typical target for the Punjab's fish team is the pool of murky water that forms every year in a depression squeezed between a flyover and a brick factory in an unlovely outskirt of Lahore.
It is one of the hundreds of glorified puddles that fill during the monsoon season that are of little interest to anyone apart from wallowing water buffaloes that make their home there.
Every few months a team led by a white bearded technician in a lab coat returns to the pool, tests the water and then releases up to a thousand voracious tilapia fish.
Immediately on their release the surface of the water ripples with fish rising to gobble insects and the larvae that would otherwise quickly mature into mosquitoes.
The war on mosquitoes has demanded a significant effort by Punjab's fisheries department, which runs hatcheries to breed the fish required to keep mosquitoes at bay.
The effect has been dramatic with just over 100 dengue cases reported in Punjab this year, compared with 20,000 in 2011. Officials say it has also curbed other pests, not just the Aedes mosquito that carries dengue.