Local fish face tropical threat - 18th May 2026

The Indonesian authorities are attempting to remove a fish from the country's rivers. The sapu-sapu is native to South America. However, it's also a popular choice for keeping tropical fish tanks clean.

Sapu-sapu, which is also known as the suckermouth catfish, can reach 50 centimetres in length. When they've grown too large for their aquarium, people often release them into local rivers.

As female sapu-sapu lay thousands of eggs per year, they've gradually outnumbered the populations of local fish species. They've also taken the food that these local species rely on.

In addition, sapu-sapu are well-adapted to live in Indonesia's rivers. This is due to the fact that they require less oxygen, and pollution levels are high in many of the country's rivers.

One area which is particularly badly affected is the capital, Jakarta. With 42 million people relying on its water supply, there's now a coordinated effort to solve the problem.

Local residents, sanitation workers, the fishing ministry and soldiers are working together. They're attempting to catch and clear sapu-sapu from the city's waterways.

They're collecting the fish using large nets and returning any local species to the water. In two weeks, 5.3 tonnes of sapu-sapu have been caught in South Jakarta.

The sapu-sapu are killed and then buried, which some people think is wasteful. However, the fish contain dangerous heavy metals. Mayor Muhummad Anwar outlined the risks.

Muhammad Anwar: "It contains heavy metals and is dangerous to humans."

Indonesia isn't the only place to suffer damage from alien species. In 2023, the UN reported on their financial impact. They're estimated to cost $400 billion a year in damage and lost earnings.