Jakarta. Authorities in Jakarta have launched a coordinated operation to remove invasive “janitor fish," locally known as sapu-sapu, from rivers across the capital, as officials seek to restore aquatic ecosystems disrupted by the species’ rapid spread.

The clean-up drive, ordered by Governor Pramono Anung, was carried out simultaneously on Friday in all five administrative cities of Jakarta, involving hundreds of personnel and local residents.

In East Jakarta, Mayor Munjirin led a team of around 150 personnel — including firefighters, disaster mitigation officers and local officials — to net the fish in the Ciliwung River in Kramat Jati.

“Following the governor’s instruction, we are conducting operations across 10 locations in East Jakarta, one in each district,” Munjirin said.

At the Ciliwung site alone, authorities collected about 200 kilograms of the fish, with results from nine other locations still being compiled. The fish were buried near the riverbank after collection, and officials said the operation would be repeated regularly.

Similar efforts were carried out in West Jakarta, including in waterways in Cengkareng, where joint teams swept river channels using nets to capture both adult fish and eggs. In less than two hours, crews collected around 20 kilograms of fish measuring between 20 and 30 centimeters.

West Jakarta Mayor Iin Mutmainnah introduced incentives to boost participation, offering Rp 25,000 ($1.50) per kilogram of fish collected, along with rewards for the most successful teams.

The campaign comes amid growing concern over the explosion of janitor fish populations in Jakarta’s waterways. The species, a type of armored catfish often kept in aquariums, is considered invasive and harmful to local ecosystems.

Officials say the fish feed on native species and their eggs while also damaging riverbanks and embankments, worsening erosion, and threatening flood control infrastructure.

Governor Pramono said the operation is part of a broader environmental clean-up effort aimed at improving river health across the capital, with activities also taking place in areas such as Kelapa Gading and Setu Babakan.

Environmental experts have long warned that unchecked populations of invasive species can destabilize freshwater ecosystems, particularly in densely populated urban areas like Jakarta.

City officials said the coordinated operation marks the beginning of a sustained effort to control the species, with regular monitoring and removal planned to prevent further ecological damage.

The fish, known scientifically as suckermouth catfish or plecostomus, have rapidly multiplied in Jakarta’s rivers and canals. Native to South America, the species is considered highly adaptable and has become invasive in several regions worldwide.

Commonly dubbed “janitor fish” for their ability to consume algae, the species is popular in aquariums. However, once released into the wild, often by pet owners, they can spread rapidly and outcompete native species.

The fish can grow up to 50 centimeters in length and live for 10 to 15 years. As opportunistic omnivores, they feed on algae, aquatic plants, invertebrates, and small fish, allowing them to dominate local ecosystems. 

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