SINGAPORE - National water agency PUB has released tens of thousands of guppies, mollies and swordtails in Pandan Reservoir to help to control the midge population, following a recent surge in the insects in the surrounding area.

The agency released the fishes in a controlled manner that does not affect the reservoir's ecosystem, it said in a Facebook post on Friday (Sept 6). The fishes eat the pupae of midges in the water.

"We have also installed insect nets at bus stops along Penjuru Road and West Coast Road to deter midges from entering the bus stop area," it said.

PUB added that its officers continue to work on the ground daily in Teban Gardens, next to Pandan Reservoir, to reduce the midge nuisance to residents.

On Monday (Sept 2), Minister for the Environment and Water Resources Masagos Zulkifli said in Parliament that PUB is ramping up its efforts to stamp out midge swarms at reservoirs.

The measures target the current dominant midge species, which is rare, he said.

They include greasing drain walls to trap midges when they land to rest, and placing an extra kilometre of netting on reservoir dykes to capture adult midges that might be blown into residential estates.

Mr Masagos, replying to three MPs on measures to address the problem at Pandan Reservoir, said the outbreak is different from the last midge flare-up in 2016.

Unlike common midges, he explained the rare species hides in drains during the day and swarms above them in the evening.

He attributed their fast growth this year to an unusually hot July, the second warmest since 1929.

While midges do not bite or spread diseases, they can be a nuisance when present in large numbers.