Invasive blackchin tilapia wiping out Bangkok shrimp farms

Local shrimp farmers in Bangkok’s Bang Khun Thian district are facing severe financial losses as the invasive blackchin tilapia population explodes, decimating their yields and forcing them to pivot to catching the pest species just to survive.

Today, a group of over 20 aquaculture farmers gathered in the Samae Dam sub-district to drain a 6.4 hectare shrimp pond and haul out an astonishing 20 tonnes of blackchin tilapia.

The operation began at 3am, with workers corralling the fish into nets, loading them into 40-kilogram baskets and using boats and pickup trucks to transport the catch to buyers at the Talad Thai wholesale market.

The sheer volume of the invasive fish highlights a worsening crisis. Farmers were reported catching only three tonnes of blackchin tilapia from the same pond last year, compared to nearly 20 tonnes this year.

Observers noted that many of the fish caught were exceptionally large, weighing between 3 to 4 kilograms each. Local farmers explained that the pond had not been completely cleared for a year, in hopes of harvesting shrimp. Instead, their 2025 revenues were cut by more than half because the predatory tilapia devoured the shrimp.

"No one wants to raise these fish," one frustrated shrimp farmer said, dismissing online rumors that locals were intentionally breeding blackchin tilapia for sale. "Before this infestation, we could make 10,000 to 20,000 baht a day selling shrimp. Today, there are barely any shrimp left."

Today’s haul marked the second major clearing operation at the site.

On May 9, farmers caught 10 tonnes of the fish but were unable to clear the entire pond due to labour shortages and buying queues at the market.

The delay caused the remaining oxygen-depleted fish to die and float to the surface en masse.

The operation was observed by Naruephol Lertpunyaroj, a Bangkok MP for the Bang Khun Thian-Bang Bon constituency representing the People's party.

While welcoming the government's adding of the blackchin tilapia outbreak to the national agenda, Naruephol urged authorities to translate words into consistent action, saying "The declaration must come with continuous implementation, not sporadic efforts that allow the fish to breed out of control."

He also urged the government to establish clear utilisation plans for the fish, such as processing them into fertiliser or food products.

Furthermore, Naruephol called for a guaranteed, subsidised purchasing price to incentivise farmers to hunt the fish in natural waterways, noting that the current high cost of fuel makes independent eradication efforts financially unsustainable for locals.