Local fish face tropical threat - 18th May 2026

The sapu-sapu fish is the target of a nationwide campaign in Indonesia. This invasive species, also known as the suckermouth catfish, originates from South America.

The species was first introduced to Southeast Asia to keep aquariums clean. However, these tropical fish often measure 50 centimetres when fully grown, at which point they're too big for their tanks.

These large specimens are frequently thrown into nearby rivers. With female sapu-sapu producing thousands of eggs a year, their numbers have now overtaken those of indigenous fish species. They're also consuming the food sources these local species depend on.

The success of this invasive species is also due to high levels of pollution in many of Indonesia's rivers. Two of Indonesia's major rivers are among the most polluted in the world. Sapu-sapu require less oxygen to survive and can tolerate pollutants better than many indigenous species.

The water-stressed area around the capital, home to 42 million people, is particularly badly affected. Local residents, sanitation workers, fishing ministry workers and soldiers are collaborating to remove the fish.

In 2 weeks, these efforts have seen 5.3 tonnes of sapu-sapu removed in South Jakarta alone. After being caught in large nets, the heads are removed from the sapu-sapu, which are then buried, while any indigenous fish are returned.

Some question whether these sapu-sapu could be processed for fish leather or animal feed. However, the mayor of South Jakarta, Muhammad Anwar, lays out the dangers this would present.

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

The threats from invasive species aren't only an issue in Indonesia. According to a UN assessment in 2023, they cost $400 billion a year in lost income and damages.