Suckermouth Catfish Surge Signals Ecological Alarm in Jakarta's Rivers

TEMPO.CO, Jakarta - The rapid spread of suckermouth catfish, locally known as sapu-sapu, in Indonesia’s urban rivers is less about the species itself and more about worsening water quality, according to an academic from Universitas Airlangga.

Veryl Hasan, an assistant professor of aquaculture at the university’s Faculty of Fisheries and Marine Sciences, said the fish, commonly found in heavily polluted waterways such as those in Jakarta, have become dominant because they can survive where most native species cannot.

“Sapu-sapu fish are highly tolerant of poor environmental conditions. When rivers become heavily polluted, many local fish die, while this species continues to survive and reproduce rapidly,” Veryl said in a written statement on Friday, April 24, 2026.

Originally from South America, suckermouth catfish are not considered invasive in their native habitat and are even consumed by local communities. Problems arise, however, when they are introduced into Indonesian waters without natural predators to keep their population in check.

Their adaptability is compounded by their feeding behavior. Veryl described them as opportunistic feeders, capable of consuming a wide range of resources, from aquatic plants to small organisms, allowing them to outcompete native fish for food and space.

This combination of resilience and lack of predators enables their population to grow rapidly, particularly in degraded ecosystems. In healthier rivers, however, their numbers tend to be more balanced due to competition with other species.

Veryl said the phenomenon highlights a broader ecological issue rather than just a species problem. Efforts to control the population, he argued, should focus not only on removal but also on restoring river health.

He called for stricter enforcement of regulations prohibiting the release of non-native fish into natural waterways, along with stronger monitoring on the ground. Improving water quality through pollution control, he added, is essential to allow native fish populations to recover and rebalance the ecosystem.

“The key is not just catching sapu-sapu fish, but improving the river habitat itself,” he said.

As a supplementary measure, he suggested controlled harvesting of the fish, for example by using them as raw material for animal or ornamental fish feed. He also urged the public not to release unwanted exotic fish into rivers.

“If people can no longer care for them, they should sell them to responsible hobbyists or dispose of them properly, not release them into the wild,” he said.