Minister Orders Probe After Mass Fish Death in Rangsit Canal
Large numbers of dead fish were found in Rangsit Canal in Pathum Thani, with black, foul-smelling water and zero dissolved oxygen recorded at one site. Minister Sajja Chomglin ordered the Pollution Control Department to investigate water quality and coordinate cleanup efforts, while warning the public to avoid contact with the water. Laboratory analysis of water samples is underway, with results expected within a week.
Natural Resources and Environment Minister Sajja Chomglin expressed concern over large numbers of dead fish found in Rangsit Canal, with black, foul-smelling water reported in Khlong Song and Khlong Rangsit Prayoonsak in Pathum Thani Province. He ordered the Pollution Control Department to urgently investigate water quality and coordinate with local agencies to address the pollution, while warning the public to avoid using the water to prevent health and environmental impacts.
Pollution Control Department Director-General Dr. Surinthorn Worakitthamrong said that on October 16, 2025, the Region 6 Environmental Office and Pollution Control Center surveyed five sites and collected water samples. At Khlong Song, Moo Baan Pruksa 44 — where many dead fish were found — the water had pH 7.17, dissolved oxygen (DO) of 0 mg/L, turbidity of 1,295.1 NTU, and electrical conductivity of 677 microsiemens/cm, indicating no dissolved oxygen, which could cause aquatic animals to suffocate. Preliminary water quality classified the site as surface water type 5.
At Khlong Rangsit Prayoonsak, four sampling points — including the Bueng Yi Tho municipal pier, Rangsit-Nakhon Nayok Soi 46, the Sky Bridge over Rangsit Canal, and the Chulalongkorn water gate — showed pH ranging from 6.97 to 7.02, DO between 1.41 and 2.61 mg/L, turbidity from 19.4 to 23.6 NTU, and electrical conductivity from 492 to 557 microsiemens/cm. Three points were classified as surface water type 4 and one as type 5. These are preliminary results for the specific locations and times sampled.
The Region 6 office sent samples to a laboratory for analysis of organic substances, bacteria, ammonia, nutrients, and eight heavy metals (lead, cadmium, total chromium, copper, nickel, iron, manganese, and zinc). Results are expected within about seven days to fully assess water quality and determine the cause of the fish deaths. Field test kits detected no arsenic, and measurements of volatile organic compounds (VOCs) and hydrogen sulfide gas (H₂S) at all five sites found none.
The Pollution Control Department warned the public not to consume dead fish and to avoid direct contact with the canal water; if contact is necessary, wear gloves and boots and wash immediately. It also urged people to reduce dumping waste and discharging wastewater into waterways.
The department will continue to monitor the lab results and coordinate with relevant agencies to establish corrective measures and ongoing surveillance. Members of the public can report incidents or seek advice from the Region 6 Office in Nonthaburi at telephone 02 968 8065 or the Pollution Control Department hotline 1650.
