- The head of a Thai NGO focused on agricultural monitoring and food sovereignty is being sued by agribusiness giant Charoen Pokphand Foods (CPF) for alleging the firm is linked to the outbreak of an invasive fish species in Thailand’s waterways.
- The lawsuit has been slammed as a SLAPP (strategic lawsuit against public participation) and a tactic to divert attention away from containing the outbreak and identifying the source and parties responsible.
- The blackchin tilapia has spread to at least 19 provinces, where it outcompetes wild and commercially viable aquatic species, disturbing ecosystems and devastating farmers’ livelihoods.
- The case comes as Thailand awaits public hearing of new anti-SLAPP regulations aimed at curbing judicial harassment.
The secretary-general of a Thai agricultural watchdog is facing a lawsuit that observers say is part of corporate efforts to silence citizens who are calling for greater accountability over the outbreak of an invasive species of fish wreaking havoc in Thailand’s waterways.
Witoon Lianchamroon of the BIOTHAI Foundation, a Thailand-based food sovereignty NGO, appeared at Nonthaburi Provincial Court Oct. 22 for the first hearing of a defamation lawsuit filed against him by Charoen Pokphand Foods (CPF). The firm, a subsidiary of Thailand’s largest agricultural conglomerate, CP Group, alleges he spread false and misleading information linking it to the outbreak of blackchin tilapia (Sarotherodon melanotheron), a highly invasive species of fish.
The case stems from a public conference hosted by the BIOTHAI Foundation in July 2024, when Witoon alleged during a presentation that the invasive fish outbreak was linked to an aquaculture facility operated by CPF in Samut Songkhram province. At the event, Witoon also urged the firm to take responsibility for losses to farmers’ livelihoods and the outbreak’s escalating ecological harms.
Blackchin tilapia, a species native to brackish coastal habitats in West Africa, breeds rapidly year-round, can survive in both freshwater and saltwater, and has an omnivorous diet. As such, it has outcompeted both native and commercially farmed species, harming aquaculture businesses in at least 19 provinces where it has already spread.
CPF came under scrutiny over the matter because it obtained a permit from the Department of Fisheries to import the species in 2010, shortly before the first detections in the wild in the same province as its research facility.
According to local media reports, CPF says it destroyed all of the imported fish after its experiment at the facility failed, and denies responsibility for the outbreak. The firm also maintains that some of the photographs Witoon presented as evidence were inaccurate, alleging the images were misattributed or out of date. CPF did not respond to Mongabay’s requests for comment for this story.
At the hearing, CPF alleged the material presented at the July 2024 conference and subsequently shared online harmed the company’s reputation. It said its revenues had plummeted since then, sources who were in the courtroom told Mongabay.
CPF is seeking 200 million baht ($6.17 million) in compensation in two separate claims of defamation by publication made jointly against Witoon and the BIOTHAI Foundation.
Witoon pleaded not guilty to each of the counts brought against him. He told Mongabay his actions to provide evidence of the outbreak were in the public interest. The next hearing of the defamation lawsuit is set for Dec. 1.
Observers have slammed the defamation allegations, labeling them an example of SLAPP (strategic lawsuit against public participation) tactics that are typically filed by companies with the goal of intimidating and silencing their critics.

Angus Lam, Asia lead for GRAIN, a nonprofit supporting small farmers, said the lawsuit diverts attention away from efforts to identify the source of the blackchin tilapia outbreak and contain it. These delays will benefit the firm, he said, which is already the dominant player in Thailand’s aquaculture industry.
The dominance of blackchin tilapia in not only brackish waterways, but increasingly also in many freshwater systems in Thailand, means many farmers have been compelled to switch to “intensive, closed systems that rely on feed, chemicals and antibiotics supplied by CP,” Lam said. He also noted that a representative of Thailand’s Rights and Liberties Protection Department (RLPD) in the Ministry of Justice has described the case as a SLAPP lawsuit.
The United National special rapporteur on the situation of human rights defenders, Mary Lawlor, also commented online that she would be following the court proceedings closely to ensure Thailand upholds its citizen rights’ standards.
Farmers’ groups have repeatedly rallied against the outbreak, urging the government to eradicate the invasive species, compensate affected farmers and hold the parties responsible for the outbreak accountable.
While Thailand’s government taken various measures to stem the outbreak, such as introducing native predators, releasing blackchin tilapia genetically modified to produce infertile offspring, and incentivizing people to catch blackchin tilapia through a buyback scheme, the fish remains a major scourge in many provinces.
Fishers are also yet to receive compensation for livelihood losses due to the invasion, according to Witoon. “Farmers have lost their land, they have a lot of debt, and they have a lot of problems” due to the spread of the blackchin tilapia, he said.
Representatives of fishing communities in the 19 affected provinces assembled outside the courtroom alongside environmental youth activists on Oct. 22 to demonstrate support for Witoon and the BIOTHAI Foundation. They submitted a petition to government officials, calling for serious action to address the outbreak.
The group also officially launched a mobile phone application called “Alien Hunter Thailand” that uses the iNaturalist database to provide real-time, interactive updates and encourage citizen science participation in pinpointing the spread of the invasive fish.
The group Thailand Science Research and Innovation calculated in 2024 that if the outbreak continues at its current intensity, blackchin tilapia could be present in 45 of Thailand’s 76 provinces within the next five years.
The case comes as new anti-SLAPP regulations aimed at curbing judicial harassment await public hearing in Thailand. Earlier reforms to national anticorruption legislation were criticized by legal rights groups as not going far enough to protect citizens against SLAPP lawsuits. The draft anti-SLAPP law, submitted to the House of Representatives in October, proposes exempting good-faith public interest statements from defamation charges.
Banner image: Blackchin tilapia harvested by local fishers in Prachuap Khiri Khan province in May 2025. Image by Carolyn Cowan/Mongabay.
Carolyn Cowan is a staff writer for Mongabay.
Citation:
Chaianunporn, T., Panthum, T., Singchat, W., Chaianunporn, K., Suksavate, W., Chaiyes, A., … Srikulnath, K. (2024). Sustainable ecosystem management strategies for tackling the invasion of blackchin tilapia (Sarotherodon melanotheron) in Thailand: Guidelines and considerations. Animals, 14(22), 3292. doi:10.3390/ani14223292
See related story:
Thai farmers demand action to restore ecosystems, compensate for invasive fish
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