Thailand boasts some of the most diverse ecosystems on the planet. From the lush forests of the north to the mangroves of the south, this country is a sanctuary for a plethora of wildlife species. These natural systems have evolved over millennia, during which time plant and animal species have slowly moved across the landscape as climatic and ecological conditions changed. These species adapted to their new environments, and the systems adapted to them. But times have changed, and species now move from their native environments across the globe at the speed of shipping, air transport, and rail. This results in the rapid invasion of new species into environments that have few natural mechanisms to keep them in balance with native species or the built environment.
Thailand has a diverse range of plant and animal species, but throughout history, we have faced numerous invasions by non-native species – especially in our aquatic systems – from water hyacinth, sucker catfish, to golden apple snails and most recently – Blackchin tilapia, known locally as pla mor kaang dum. This latest invasion serves as a stark example of the havoc that invasive species can wreak. Originally from Ghana in West Africa, it appears to be proliferating at an alarming rate, potentially endangering over 800 native freshwater fish species, and causing widespread economic destruction. The urgency to address this looming crisis cannot be overstated, yet it appears that the gravity of the situation has not fully resonated with the relevant authorities and the broader public.
The threat extends beyond ecological disruption. There is a real danger that the Blackchin tilapia could spread to major water bodies such as the Chao Phraya River, which serves as a lifeline for millions of people. The river is a crucial source of water for transportation, irrigation, and industry, and it supports a variety of aquatic life. An unchecked invasion of this species could lead to a cascade of ecological consequences, affecting water quality and the livelihoods of communities that depend on the river. Like most invasive species, it thrives in a wide range of environmental conditions, making it a resilient and challenging invasive species to control.
Other species, such as the sucker catfish, native to South America, were introduced to Thailand for their perceived benefits in controlling algae in aquariums and ponds. However, once released into natural water bodies, the catfish has become a formidable invasive force. Its ability to thrive in various environmental conditions, coupled with its aggressive feeding habits, make it a serious threat to native fish and aquatic plants.
Another example is the golden apple snail, or hoy cherry. Initially introduced as a potential food source, it became an ecological and economic nightmare, spreading rapidly through the country’s rice paddies, devouring young rice plants and causing significant crop damage. The ecological impact was severe, as the snails disrupt local ecosystems, outcompete native species and alter habitats. Economically, farmers face devastating losses, with reduced rice yields leading to increased costs and financial hardship.
Not all aquatic invaders are fish. The water hyacinth, also known locally as Java leaves, has created another long-standing environmental crisis. This invasive plant has spread unchecked across waterways for decades. Originally introduced for ornamental purposes, it thrives in the country’s warm, nutrient-rich waters. Its rapid proliferation forms dense mats that block sunlight, suffocate aquatic life, and impede water flow.
The economic impact has been profound. Fishermen struggle as fish populations decline, caught in the chokehold of the hyacinth. Agricultural sectors suffer as irrigation systems clog, reducing crop yields and increasing costs. The tourism industry, vital to Thailand’s economy, also takes a hit, with scenic waterways turned into unsightly, impassable thickets.
In light of ongoing challenges faced here in Thailand, there is much to be gained from examining the experiences in other regions that have faced similar challenges. Take, for example, the United States’ battle against the invasive Asian carp, which has devastated native fish populations in the Mississippi River basin. Efforts to control their spread have included physical barriers, targeted fishing, and public education campaigns. By studying these efforts, Thailand can develop effective strategies tailored to its unique ecological and socio-economic context.
Invasive species such as Quagga mussels and Zebra mussels have also wreaked havoc on North American ecosystems, fundamentally altering aquatic environments. These bivalves, introduced through ballast water discharge, proliferate rapidly and attach to any available surface, including boats, docks, and water intake pipes. Their filtration of water strips essential nutrients, such as phytoplankton, disrupting the food web and starving native species. Economic cost in the US alone has reached $500 million (18 billion baht) annually.
Addressing the threat of invasive species requires a multi-faceted approach. Prevention is the most effective strategy, including strict regulations on the importation and release of non-native species.
The best way by far to combat the threat of invasive species is to prevent their introduction in the first place. Strict regulations should be in place to control the importation and release of non-native species, and those who ignore these regulations should be held accountable and take full responsibility for their actions. Public awareness campaigns can help educate people about the risks associated with introducing foreign species into local ecosystems. Research and monitoring are also crucial components of an effective response
The story of aquatic invaders in Thailand, with the rapid spread of Blackchin tilapia being a classic example, is a cautionary tale about the fragility of our natural ecosystems. It underscores the importance of preserving biodiversity and the need for vigilant protection against the introduction of invasive species. As Thailand grapples with the challenges posed by invasive species — both in our waters and on land — it must also recognise the value of its native wildlife and the irreplaceable role it plays in maintaining ecological balance and enriching our lives. Only through concerted and sustained efforts from both public and private sectors can the threat of invasive species be mitigated, ensuring a vibrant and thriving natural world for future generations.
About WWF in Thailand
WWF is one of the world’s largest and most respected independent conservation organizations, with over 5 million supporters and a global network active in nearly 100 countries. WWF’s mission is to stop the degradation of the Earth’s natural environment and to build a future in which humans live in harmony with nature, by conserving the world’s biological diversity, ensuring that the use of renewable natural resources is sustainable, and promoting the reduction of pollution and wasteful consumption. WWF has had a presence in Thailand since 1995. WWF-Thailand works with government, civil society, and private sector partners to address the threats to biodiversity and to move towards a greener nature-based future. Learn more at www.wwf.or.th.
For more information, please kindly contact:
Oranit Bunyaprasit – Head of Communications oranitb@wwf.or.th
Sopahpen Grachangnetara – Senior Communications Officer sopahpeng@wwf.or.th
Natnicha Petsakul – Communications Officer natnichap@wwf.or.th
