Ngintir Kali, Campaign Encourages Public to Love Brantas River Fish

The ECOTON team carried out a 'Ngintir Kali' (Drifting and swiming in the
River current) along the Surabaya River on Sunday (May 31).

(Ngintir Kali = drifting and Swimming in the river current)

May 31, 2026 / Surabaya – “The Brantas River still has the potential to recover and once again become a thriving fish habitat. Recent research has documented 34 fish species in the Surabaya River and 42 fish species in the Brantas River. These findings can serve as a strong foundation for the people of East Java to restore the water quality of both the Brantas and Surabaya Rivers,” said Rulli Mustika Adya, Director of Posko Ijo. Rulli emphasized the need for a large-scale public campaign to introduce native Brantas River fish species to the people of East Java.

To support this effort, Ecoton launched the Ngintir Kali Surabaya (Surabaya River Patrol) program, which began on Saturday, May 30, 2026. The Ngintir Kali Surabaya River Patrol Team consists of seven members: four people conducting the river patrol and three members of the ground team responsible for water quality testing and documentation. Participants come from the Riverbank Community Alliance (AKAMSI), the Ecological Observation and Wetlands Conservation Foundation (ECOTON), Posko Ijo, River Warrior, and TitikTerang. Previously, in 2025, Ecoton conducted a similar Surabaya River Patrol from the Mlirip Water Gate in Mojokerto to Gunungsari in Surabaya.

“For three days in 2025, we patrolled the Surabaya River. However, when we reached the Karang Pilang Bridge area, we had to continue the patrol by boat because the river water smelled strongly of pollution. One of our team members even suffered an ear infection that caused swelling,” explained Alaika Rahmatullah.

The coordinator of the Ecoton River Patrol further explained that the Ngintir Kali Surabaya program has five main objectives: Introducing the diversity of fish species in the Brantas River

1. Identifying sources of industrial pollution
2. Mapping plastic waste accumulation in the Surabaya River
3. Identifying illegal constructions along the Surabaya Riverbanks
4. Conducting microplastic and water quality testing
5. Fish Threatened by Microplastic Pollution

This initiative is being carried out because the freshwater fish biodiversity of the Brantas River is currently under threat from microplastic pollution originating from recycling industries, household plastic waste along the Brantas watershed, and the massive conversion of riverbanks into residential and industrial developments.

Nevertheless, there is new hope with the discovery of three endemic Javan fish species in the Surabaya River, despite the fact that this 41-kilometer river remains heavily polluted.

In March 2026, research conducted in the Surabaya River identified 34 freshwater fish species, including three species endemic to Java (found only on the island of Java):

1. Rengkik or Asian Catfish (Hemibagrus nemurus)
2. Javan Catfish with venomous spines (Clarias batrachus)
3. Spotted Barb (Barbodes binotatus)

Earlier research conducted between 2021 and 2022 by fisheries scientists from universities in Indonesia, Malaysia, and Brazil found that the Brantas River is home to 42 freshwater fish species belonging to 35 genera and 21 families. The Cyprinidae family—commonly known as bader, wader, and tawes fish—was the most dominant group, represented by 12 genera and 15 species.

“Restore Brantas, Bring Back the Rengkik”

The 2026 Ngintir Kali Surabaya campaign invites the people of East Java to protect, preserve, and maintain the Brantas River ecosystem, which serves as a vital source of life for local communities. The river supplies raw water for municipal drinking water companies (PDAM) in Surabaya, Sidoarjo, Gresik, Mojokerto, and Jombang, while also supporting one of Indonesia’s most important agricultural regions. “Besides supplying water for drinking water utilities and irrigation, hundreds of large industries depend on Brantas River water as a key raw material in their production processes. Unfortunately, rather than giving back to the river, many industries discharge untreated wastewater, resulting in recurring incidents of mass fish deaths,” said Jofan Ahmad Arianto.

The AKAMSI activist further urged industries along the Brantas River to make meaningful contributions toward restoring the water quality of the Surabaya River.

The campaign will conclude with a theatrical demonstration at the Grahadi State Building on June 5, 2026, in commemoration of World Environment Day.

“This theatrical action is intended to remind the people of East Java that there is still hope for restoring the water quality of the Brantas River. It will require collective action to combat microplastic pollution from industry, settlements, and policies that must become more supportive of the Brantas River,” concluded Rulli Mustika Adya.